[animations] Remove .flutter-plugins reference from example app (#8002)
Removes .flutter-plugins reference from example by (1) deleting the packages/animations/example/android directory, (2) running (in the packages/animations directory)
```
flutter create example --platforms android -a kotlin --org "dev.flutter.packages.animations"
```
and then (3) manually made the following changes:
- Added back packages/animations/example/android/.pluginToolsConfig.yaml (removed by command)
- Updated the Gradle version from 8.7 to 8.3 (downgraded by command)
- Deleted example/analysis_options.yaml (added by command)
- Deleted example/test/ (added by command)
- Added back artifact hub
- Removed template TODOs
- Bumped Kotlin Gradle version to 1.9.0
- Bumped AGP version from 8.1.0 to 8.5.1.
Part of https://github.com/flutter/flutter/issues/157660.
[animations] Remove .flutter-plugins reference from example app (#8002)
Removes .flutter-plugins reference from example by (1) deleting the packages/animations/example/android directory, (2) running (in the packages/animations directory)
```
flutter create example --platforms android -a kotlin --org "dev.flutter.packages.animations"
```
and then (3) manually made the following changes:
- Added back packages/animations/example/android/.pluginToolsConfig.yaml (removed by command)
- Updated the Gradle version from 8.7 to 8.3 (downgraded by command)
- Deleted example/analysis_options.yaml (added by command)
- Deleted example/test/ (added by command)
- Added back artifact hub
- Removed template TODOs
- Bumped Kotlin Gradle version to 1.9.0
- Bumped AGP version from 8.1.0 to 8.5.1.
Part of https://github.com/flutter/flutter/issues/157660.