fix: process upload only after successful remote sync (#22360)

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>

mobile/lib/domain/services/sync_stream.service.dart

@@ -23,7 +23,7 @@ class SyncStreamService {
 
   bool get isCancelled => _cancelChecker?.call() ?? false;
 
-  Future<void> sync() async {
+  Future<bool> sync() async {
     _logger.info("Remote sync request for user");
     // Start the sync stream and handle events
     bool shouldReset = false;
@@ -32,6 +32,7 @@ class SyncStreamService {
       _logger.info("Resetting sync state as requested by server");
       await _syncApiRepository.streamChanges(_handleEvents);
     }
+    return true;
   }
 
   Future<void> _handleEvents(List<SyncEvent> events, Function() abort, Function() reset) async {