show ml consent banner after syncing flags only

mobile/lib/ui/home/status_bar_widget.dart

@@ -39,6 +39,7 @@ class _StatusBarWidgetState extends State<StatusBarWidget> {
   bool _showStatus = false;
   bool _showErrorBanner = false;
   bool _showMlBanner = !flagService.hasGrantedMLConsent &&
+      flagService.hasSyncedAccountFlags() &&
       !localSettings.hasSeenMLEnablingBanner;
   Error? _syncError;
 

mobile/plugins/ente_feature_flag/lib/src/service.dart

@@ -60,6 +60,10 @@ class FlagService {
 
   String get castUrl => flags.castUrl;
 
+  bool hasSyncedAccountFlags() {
+    return _prefs.containsKey("remote_flags");
+  }
+
   Future<void> setMapEnabled(bool isEnabled) async {
     await _updateKeyValue("mapEnabled", isEnabled.toString());
     _updateFlags(flags.copyWith(mapEnabled: isEnabled));