Reverts "Warn when Gradle plugins are applied using the legacy "apply script method" way" (#140102)

Reverts flutter/flutter#139690
Initiated by: hellohuanlin
This change reverts the following previous change:
Original Description:
This PR adds a deprecation message when Android build is using the legacy "apply script method" way of applying Flutter's Gradle plugins (that is: [`flutter.gradle`](https://github.com/flutter/flutter/blob/3.16.0/packages/flutter_tools/gradle/flutter.gradle) and [`app_plugin_loader.gradle`](https://github.com/flutter/flutter/blob/3.16.0/packages/flutter_tools/gradle/app_plugin_loader.gradle)).

See also:
- #121541
  - in particular https://github.com/flutter/flutter/issues/121541#issuecomment-1836947311
- #135392
  - and PR that add the migration guide: [#9857](https://github.com/flutter/website/pull/9857)

- I think either `logger.error` or `logger.quiet` must be used, because all other error levels are not shown during `flutter build apk` (and that's what most people use).

packages/flutter_tools/gradle/app_plugin_loader.gradle

@@ -5,11 +5,5 @@
 // This file exists solely for the compatibility with projects that have
 // not migrated to the declarative apply of the Flutter App Plugin Loader Gradle Plugin.
 
-logger.error("You are applying Flutter's app_plugin_loader Gradle plugin \
-imperatively using the apply script method, which is deprecated and will be \
-removed in a future release. Migrate to applying Gradle plugins with the \
-declarative plugins block: https://flutter.dev/go/flutter-gradle-plugin-apply\n\
-")
-
 def pathToThisDirectory = buildscript.sourceFile.parentFile
 apply from: "$pathToThisDirectory/src/main/groovy/app_plugin_loader.groovy"

packages/flutter_tools/gradle/flutter.gradle

@@ -5,10 +5,5 @@
 // This file exists solely for the compatibility with projects that have
 // not migrated to the declarative apply of the Flutter Gradle Plugin.
 
-logger.error("You are applying Flutter's main Gradle plugin imperatively using \
-the apply script method, which is deprecated and will be removed in a future \
-release. Migrate to applying Gradle plugins with the declarative plugins \
-block: https://flutter.dev/go/flutter-gradle-plugin-apply\n")
-
 def pathToThisDirectory = buildscript.sourceFile.parentFile
 apply from: "$pathToThisDirectory/src/main/groovy/flutter.groovy"

packages/flutter_tools/test/integration.shard/android_gradle_deprecated_plugin_apply_test.dart

-// Copyright 2014 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:convert';
-
-import 'package:file/file.dart';
-import 'package:flutter_tools/src/base/io.dart';
-
-import '../src/common.dart';
-import 'test_utils.dart';
-
-void main() {
-  late Directory tempDir;
-
-  setUp(() async {
-    tempDir = createResolvedTempDirectorySync('run_test.');
-  });
-
-  tearDown(() async {
-    tryToDelete(tempDir);
-  });
-
-  testWithoutContext(
-      'gradle prints warning when Flutter\'s Gradle plugins are applied using deprecated "apply plugin" way', () async {
-    // Create a new flutter project.
-    final String flutterBin =
-    fileSystem.path.join(getFlutterRoot(), 'bin', 'flutter');
-    ProcessResult result = await processManager.run(<String>[
-      flutterBin,
-      'create',
-      tempDir.path,
-      '--project-name=testapp',
-    ], workingDirectory: tempDir.path);
-    expect(result.exitCode, 0);
-    // Ensure that gradle files exists from templates.
-    result = await processManager.run(<String>[
-      flutterBin,
-      'build',
-      'apk',
-      '--config-only',
-    ], workingDirectory: tempDir.path);
-    expect(result.exitCode, 0);
-
-    // Change build files to use deprecated "apply plugin:" way.
-    // Contents are taken from https://github.com/flutter/flutter/issues/135392 (for Flutter 3.10)
-    final File settings = tempDir.childDirectory('android').childFile('settings.gradle');
-    final File buildGradle = tempDir.childDirectory('android').childFile('build.gradle');
-    final File appBuildGradle = tempDir.childDirectory('android').childDirectory('app').childFile('build.gradle');
-    settings.writeAsStringSync(r'''
-include ':app'
-
-def localPropertiesFile = new File(rootProject.projectDir, "local.properties")
-def properties = new Properties()
-
-assert localPropertiesFile.exists()
-localPropertiesFile.withReader("UTF-8") { reader -> properties.load(reader) }
-
-def flutterSdkPath = properties.getProperty("flutter.sdk")
-assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
-apply from: "$flutterSdkPath/packages/flutter_tools/gradle/app_plugin_loader.gradle"
-'''
-    );
-  buildGradle.writeAsStringSync(r'''
-buildscript {
-    ext.kotlin_version = '1.7.10'
-    repositories {
-        google()
-        mavenCentral()
-    }
-
-    dependencies {
-        classpath 'com.android.tools.build:gradle:7.3.0'
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-    }
-}
-
-allprojects {
-    repositories {
-        google()
-        mavenCentral()
-    }
-}
-
-rootProject.buildDir = '../build'
-subprojects {
-    project.buildDir = "${rootProject.buildDir}/${project.name}"
-}
-subprojects {
-    project.evaluationDependsOn(':app')
-}
-
-tasks.register("clean", Delete) {
-    delete rootProject.buildDir
-}
-''');
-  appBuildGradle.writeAsStringSync(r'''
-def localProperties = new Properties()
-def localPropertiesFile = rootProject.file('local.properties')
-if (localPropertiesFile.exists()) {
-    localPropertiesFile.withReader('UTF-8') { reader ->
-        localProperties.load(reader)
-    }
-}
-
-def flutterRoot = localProperties.getProperty('flutter.sdk')
-if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
-}
-
-def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
-if (flutterVersionCode == null) {
-    flutterVersionCode = '1'
-}
-
-def flutterVersionName = localProperties.getProperty('flutter.versionName')
-if (flutterVersionName == null) {
-    flutterVersionName = '1.0'
-}
-
-apply plugin: 'com.android.application'
-apply plugin: 'kotlin-android'
-apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
-
-android {
-    compileSdkVersion flutter.compileSdkVersion
-    ndkVersion flutter.ndkVersion
-    namespace "com.example.testapp"
-
-    compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_8
-        targetCompatibility JavaVersion.VERSION_1_8
-    }
-
-    kotlinOptions {
-        jvmTarget = '1.8'
-    }
-
-    sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
-    }
-
-    defaultConfig {
-        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
-        applicationId "com.example.testapp"
-        // You can update the following values to match your application needs.
-        // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-build-configuration.
-        minSdkVersion flutter.minSdkVersion
-        targetSdkVersion flutter.targetSdkVersion
-        versionCode flutterVersionCode.toInteger()
-        versionName flutterVersionName
-        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
-    }
-
-    buildTypes {
-        release {
-            // TODO: Add your own signing config for the release build.
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig signingConfigs.debug
-        }
-    }
-}
-
-flutter {
-    source '../..'
-}
-
-dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-}
-''');
-
-    result = await processManager.run(<String>[
-      flutterBin,
-      'build',
-      'apk',
-      '--debug',
-    ], workingDirectory: tempDir.path);
-    expect(result.exitCode, 0);
-    // Verify that stderr output contains deprecation warnings.
-    final List<String> actualLines = LineSplitter.split(result.stderr.toString()).toList();
-    expect(
-      actualLines.any((String msg) => msg.contains(
-        "You are applying Flutter's main Gradle plugin imperatively"),
-      ),
-      isTrue,
-    );
-    expect(
-      actualLines.any((String msg) => msg.contains(
-        "You are applying Flutter's app_plugin_loader Gradle plugin imperatively"),
-      ),
-      isTrue,
-    );
-  });
-}