fix: update file skipping logic in Google Drive indexer

- Modified the `_should_skip_file` function to prevent skipping of documents with a FAILED status, ensuring they are reprocessed even if their content remains unchanged.
- Added a new integration test to verify that FAILED documents are not skipped during the indexing process.

surfsense_backend/app/tasks/connector_indexers/google_drive_indexer.py

@@ -149,7 +149,7 @@ async def _should_skip_file(
         return True, f"File renamed: '{old_name}' → '{file_name}'"
 
     if not DocumentStatus.is_state(existing.status, DocumentStatus.READY):
-        existing.status = DocumentStatus.ready()
+        return False, None
     return True, "unchanged"