Revert Copilot suggestion: and project_client is unnecessary.

`project_client` is always initialized before thread creation, so `if thread:` is sufficient.

Author: Prasanjeet-Microsoft

src/App/backend/plugins/chat_with_data_plugin.py

@@ -107,7 +107,7 @@ async def get_SQL_Response(
             logging.exception("Error in get_SQL_Response")
             return f"Error retrieving SQL data: {str(e)}"
         finally:
-            if thread and project_client:
+            if thread:
                 try:
                     logging.info(f"Attempting to delete thread {thread.id}")
                     await project_client.agents.threads.delete(thread.id)