Remove unused devicelab task gradle_non_android_plugin_test (#142742)

I moved this test to integration.shard in https://github.com/flutter/flutter/pull/80161.  Remove the no-op task https://github.com/flutter/flutter/issues/85347.

TESTOWNERS

@@ -250,14 +250,9 @@
 /dev/devicelab/bin/tasks/flutter_view_macos__start_up.dart @cbracken @flutter/desktop
 /dev/devicelab/bin/tasks/flutter_view_win_desktop__start_up.dart @yaakovschectman @flutter/desktop
 /dev/devicelab/bin/tasks/gradle_desugar_classes_test.dart @zanderso @flutter/tool
-/dev/devicelab/bin/tasks/gradle_non_android_plugin_test.dart @stuartmorgan @flutter/plugin
-/dev/devicelab/bin/tasks/gradle_non_android_plugin_test.dart @stuartmorgan @flutter/plugin
 /dev/devicelab/bin/tasks/gradle_plugin_bundle_test.dart @stuartmorgan @flutter/plugin
-/dev/devicelab/bin/tasks/gradle_plugin_bundle_test.dart @stuartmorgan @flutter/plugin
-/dev/devicelab/bin/tasks/gradle_plugin_fat_apk_test.dart @stuartmorgan @flutter/plugin
 /dev/devicelab/bin/tasks/gradle_plugin_fat_apk_test.dart @stuartmorgan @flutter/plugin
 /dev/devicelab/bin/tasks/gradle_plugin_light_apk_test.dart @stuartmorgan @flutter/plugin
-/dev/devicelab/bin/tasks/gradle_plugin_light_apk_test.dart @stuartmorgan @flutter/plugin
 /dev/devicelab/bin/tasks/hello_world_macos__compile.dart @cbracken @flutter/desktop
 /dev/devicelab/bin/tasks/hello_world_win_desktop__compile.dart @yaakovschectman @flutter/desktop
 /dev/devicelab/bin/tasks/hot_mode_dev_cycle_ios_simulator.dart @vashworth @flutter/tool

dev/devicelab/bin/tasks/gradle_non_android_plugin_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 'package:flutter_devicelab/framework/framework.dart';
-import 'package:flutter_devicelab/framework/task_result.dart';
-
-Future<void> main() async {
-  await task(() async {
-    // TODO(jmagman): Remove once gradle_non_android_plugin_test builder can be deleted, https://github.com/flutter/flutter/issues/85347
-    return TaskResult.success(null);
-  });
-}