[google_sign_in] Disable flaky web test (#10249)

This test is flaking very frequently on WASM. Disabling since it's disrupting the tree, and there hasn't been any progress on investigating the cause of the regression.

Tracked in flutter/flutter#176299

Author: stuartmorgan-g

packages/google_sign_in/google_sign_in_web/example/integration_test/flexible_size_html_element_view_test.dart renamed to packages/google_sign_in/google_sign_in_web/example/integration_test/flexible_size_html_element_view_test_disabled.dart

@@ -11,6 +11,10 @@ import 'package:google_sign_in_web/src/flexible_size_html_element_view.dart';
 import 'package:integration_test/integration_test.dart';
 import 'package:web/web.dart' as web;
 
+// TODO(stuartmorgan): Re-enable this test, by renaming it not to end with
+// _disabled. It is currently extremely flaky on WASM, see
+// https://github.com/flutter/flutter/issues/176299
+
 /// Used to keep track of the number of HtmlElementView factories the test has registered.
 int widgetFactoryNumber = 0;