Fix: File selection in Retrieval testing causes other options to disappear (#7759)

### What problem does this PR solve?

https://github.com/infiniflow/ragflow/issues/7753

The internal is due to when the selected row keys change will trigger a
testing, but I do not know why.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/db/services/common_service.py

@@ -254,7 +254,7 @@ class CommonService:
         # Returns:
         #     Number of records deleted
         return cls.model.delete().where(cls.model.id == pid).execute()
-
+    
     @classmethod
     @DB.connection_context()
     def delete_by_ids(cls, pids):