async fn handle_drop_flow_task(
    ddl_manager: &DdlManager,
    drop_flow_task: DropFlowTask,
) -> Result<SubmitDdlTaskResponse>async fn handle_drop_flow_task(
    ddl_manager: &DdlManager,
    drop_flow_task: DropFlowTask,
) -> Result<SubmitDdlTaskResponse>