Revert "i125138 abstract method smoke agp update (#125139)" (#126274)

This reverts commit 64591356.

#125331 
https://ci.chromium.org/p/flutter/builders/staging/Linux%20firebase_abstract_method_smoke_test?cursor=id%3E8783275059678311409&limit=200

- [ x I signed the [CLA].

dev/integration_tests/abstract_method_smoke_test/android/app/src/main/AndroidManifest.xml

@@ -18,7 +18,6 @@ found in the LICENSE file. -->
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
             android:hardwareAccelerated="true"
-            android:exported="true"
             android:windowSoftInputMode="stateVisible|adjustResize">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>

dev/integration_tests/abstract_method_smoke_test/android/build.gradle

@@ -7,14 +7,14 @@
 // See dev/tools/bin/generate_gradle_lockfiles.dart.
 
 buildscript {
-    ext.kotlin_version = '1.6.21'
+    ext.kotlin_version = '1.5.31'
     repositories {
         google()
         mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.4.1'
+        classpath 'com.android.tools.build:gradle:4.1.3'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 

dev/integration_tests/abstract_method_smoke_test/android/gradle/wrapper/gradle-wrapper.properties

 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.6.1-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7-all.zip