[CP] Integration tests support AGP 8.0 (#125686)

- Smallest change required to support host apps using agp 8.0 (#125657)

Original issue #125181
Cherry pick issue #125688

*If you had to change anything in the [flutter/tests] repo, include a
link to the migration guide as per the [breaking change policy].*

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] All existing and new tests are passing.

packages/integration_test/android/build.gradle

@@ -26,6 +26,10 @@ rootProject.allprojects {
 apply plugin: 'com.android.library'
 
 android {
+    // Conditional for compatibility with AGP <4.2.
+    if (project.android.hasProperty("namespace")) {
+        namespace 'dev.flutter.integration_test'
+    }
     compileSdkVersion 31
 
     compileOptions {

packages/integration_test/example/android/app/build.gradle

@@ -29,6 +29,10 @@ apply plugin: 'com.android.application'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
+    // Conditional for compatibility with AGP <4.2.
+    if (project.android.hasProperty("namespace")) {
+        namespace 'com.example.integration_test_example'
+    }
     compileSdkVersion flutter.compileSdkVersion
 
     compileOptions {