chore(in-app-messaging): move example app to "flutterfire-e2e-tests" Firebase project (#10052)

Author: russellwheatley

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

@@ -32,7 +32,7 @@ android {
     }
 
     defaultConfig {
-        applicationId "com.example.firebase_in_app_messaging_example"
+        applicationId "io.flutter.plugins.firebase.tests"
         minSdkVersion 19
         targetSdkVersion 31
         versionCode flutterVersionCode.toInteger()