ensure None returned for close_command

Signed-off-by: varun-edachali-dbx <varun.edachali@databricks.com>

Author: varun-edachali-dbx

src/databricks/sql/backend/thrift_backend.py

@@ -1221,5 +1221,4 @@ def close_command(self, command_id: CommandId) -> None:
 
         logger.debug("ThriftBackend.close_command(command_id=%s)", command_id)
         req = ttypes.TCloseOperationReq(operationHandle=thrift_handle)
-        resp = self.make_request(self._client.CloseOperation, req)
-        return resp.status
+        self.make_request(self._client.CloseOperation, req)