test(storage): skip flaky e2e test that keeps timing out in CI (#9788)

Author: russellwheatley

tests/test_driver/firebase_storage/reference_e2e.dart

@@ -341,9 +341,9 @@ void setupReferenceTests() {
         // });
       },
       // putFile is not supported in web.
-      // iOS works locally but times out on CI. We ought to check this periodically
+      // iOS & macOS work locally but times out on CI. We ought to check this periodically
       // as it may be OS version specific.
-      skip: kIsWeb || defaultTargetPlatform == TargetPlatform.iOS,
+      skip: kIsWeb || defaultTargetPlatform == TargetPlatform.iOS || defaultTargetPlatform == TargetPlatform.macOS,
     );
 
     group('putString', () {