[flutter_tools] fix period in URL for androidX incompat (#57182)

packages/flutter_tools/lib/src/android/gradle.dart

@@ -245,7 +245,7 @@ Future<void> buildGradleApp({
     globals.printStatus("$warningMark Your app isn't using AndroidX.", emphasis: true);
     globals.printStatus(
       'To avoid potential build failures, you can quickly migrate your app '
-      'by following the steps on https://goo.gl/CP92wY.',
+      'by following the steps on https://goo.gl/CP92wY .',
       indent: 4,
     );
   }

packages/flutter_tools/lib/src/android/gradle_errors.dart

@@ -191,7 +191,7 @@ final GradleHandledError androidXFailureHandler = GradleHandledError(
       // a plugin already migrated to AndroidX.
       globals.printStatus(
         'AndroidX incompatibilities may have caused this build to fail. '
-        'Please migrate your app to AndroidX. See https://goo.gl/CP92wY.'
+        'Please migrate your app to AndroidX. See https://goo.gl/CP92wY .'
       );
       BuildEvent(
         'gradle-android-x-failure',

packages/flutter_tools/test/general.shard/android/gradle_errors_test.dart

@@ -321,7 +321,7 @@ Command: /home/android/gradlew assembleRelease
       expect(testLogger.statusText,
         contains(
           'AndroidX incompatibilities may have caused this build to fail. '
-          'Please migrate your app to AndroidX. See https://goo.gl/CP92wY.'
+          'Please migrate your app to AndroidX. See https://goo.gl/CP92wY .'
         )
       );
       verify(mockUsage.sendEvent(