[Firebase AI] Disable some Imagen tests from CI (#1365)

* [Firebase AI] Disable some Imagen tests from CI

* Update UIHandlerAutomated.cs

Author: a-maurice

firebaseai/testapp/Assets/Firebase/Sample/FirebaseAI/UIHandlerAutomated.cs

@@ -75,15 +75,21 @@ protected override void Start()
         TestCountTokens,
         TestYoutubeLink,
         TestGenerateImage,
+#if !(FIREBASE_RUNNING_FROM_CI && !UNITY_EDITOR)
+        // Disabled from CI, because of rate limit issues
         TestImagenGenerateImage,
+#endif
         TestImagenGenerateImageOptions,
         TestThinkingBudget,
         TestIncludeThoughts,
         TestCodeExecution,
         TestUrlContext,
         TestTemplateGenerateContent,
         TestTemplateGenerateContentStream,
+#if !(FIREBASE_RUNNING_FROM_CI && !UNITY_EDITOR)
+        // Disabled from CI, because of rate limit issues
         TestTemplateImagenGenerateImage,
+#endif
       };
       // Set of tests that only run the single time.
       Func<Task>[] singleTests = {