[iOS] Fix crash when sync chain contains a device syncing tab groups (#28113)

Author: kylehickinson

chromium_src/ios/chrome/browser/shared/public/features/features.mm

@@ -0,0 +1,14 @@
+// Copyright (c) 2025 The Brave Authors. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#import "ios/chrome/browser/shared/public/features/features.h"
+
+#define IsTabGroupSyncEnabled IsTabGroupSyncEnabled_ChromiumImpl
+#include "src/ios/chrome/browser/shared/public/features/features.mm"
+#undef IsTabGroupSyncEnabled
+
+bool IsTabGroupSyncEnabled() {
+  return false;
+}