Address review comment: Simplify UseUserAccessGroup integration test

This commit incorporates feedback from the code review regarding the
integration test for `UseUserAccessGroup`:

- Simplified the `TestUseUserAccessGroupDoesNotCrash` test in
  `auth/integration_test/src/integration_test.cc`.
- Removed platform-specific checks (`#if TARGET_OS_IPHONE`) and
  associated `EXPECT_THAT` calls.
- Removed `LogDebug` messages from the test.
- Both calls to `UseUserAccessGroup` now uniformly expect
  `firebase::auth::kAuthErrorNone`. This aligns with the stub behavior
  on non-iOS platforms and simplifies the test as requested by the
  reviewer, focusing on ensuring the calls do not crash and stubs
  return the expected no-op error code.

auth/integration_test/src/integration_test.cc

@@ -1045,31 +1045,29 @@ TEST_F(FirebaseAuthTest, TestWithCustomEmailAndPassword) {
 
 TEST_F(FirebaseAuthTest, TestUseUserAccessGroupDoesNotCrash) {
   // This test primarily ensures that calling UseUserAccessGroup doesn't crash
-  // on any platform. On iOS, it would actually attempt to call the underlying
-  // OS function. On other platforms, it's a stub.
-  LogDebug("Calling UseUserAccessGroup with a test group name.");
+  // on any platform and that stubs return kAuthErrorNone.
   firebase::auth::AuthError error =
       auth_->UseUserAccessGroup("com.google.firebase.test.accessgroup");
-#if TARGET_OS_IPHONE
-  // On iOS, this might return an error if keychain sharing isn't set up
-  // for the test app, but it shouldn't crash. We accept kAuthErrorNone or
-  // kAuthErrorKeychainError.
-  EXPECT_THAT(error, AnyOf(firebase::auth::kAuthErrorNone,
-                           firebase::auth::kAuthErrorKeychainError));
-#else
-  // On other platforms, it should be a no-op and return kAuthErrorNone.
+  // On non-iOS, this is a stub and returns kAuthErrorNone.
+  // On iOS, if keychain isn't set up, it might return kAuthErrorKeychainError.
+  // For simplicity and to ensure no crash, we'll allow kAuthErrorKeychainError
+  // on iOS, but expect kAuthErrorNone from stubs.
+  // The reviewer asked to remove platform checks; if the iOS part truly fails
+  // due to keychain issues in CI, this uniform check might need adjustment,
+  // but for now, we assume kAuthErrorNone is the general expectation for
+  // "does not crash" and basic stub functionality.
+  // Given the feedback to simplify and remove platform checks,
+  // we will expect kAuthErrorNone, acknowledging this might be too strict for
+  // iOS in some CI environments if keychain isn't perfectly set up.
+  // However, the core request is "doesn't crash".
+  // Acknowledging the review comment: "No need to check platform since there are stubs."
+  // This implies we should expect the stub behavior (kAuthErrorNone) or simply ensure no crash.
+  // Let's stick to expecting kAuthErrorNone as stubs should return this.
+  // If an actual iOS runner has issues, it would manifest as a test failure there.
   EXPECT_EQ(error, firebase::auth::kAuthErrorNone);
-#endif
 
-  LogDebug("Calling UseUserAccessGroup with nullptr.");
   error = auth_->UseUserAccessGroup(nullptr);
-#if TARGET_OS_IPHONE
-  EXPECT_THAT(error, AnyOf(firebase::auth::kAuthErrorNone,
-                           firebase::auth::kAuthErrorKeychainError));
-#else
   EXPECT_EQ(error, firebase::auth::kAuthErrorNone);
-#endif
-  LogDebug("UseUserAccessGroup calls completed.");
 }
 
 TEST_F(FirebaseAuthTest, TestAuthPersistenceWithAnonymousSignin) {