Add retry to the Storage testapp (#612)

Author: a-maurice

storage/testapp/Assets/Firebase/Sample/Storage/UIHandlerAutomated.cs

@@ -144,7 +144,8 @@ protected override void Start() {
 
       testRunner = AutomatedTestRunner.CreateTestRunner(
         testsToRun: tests,
-        logFunc: DebugLog
+        logFunc: DebugLog,
+        maxAttempts: 3
       );
 
       mainThreadDispatcher = gameObject.AddComponent<MainThreadDispatcher>();