Function start_worker 

pub(super) fn start_worker(
    key: BatchKey,
    worker_tx: Sender<WorkerCommand>,
    workers: Arc<WorkerRegistry<BatchKey, WorkerCommand>>,
    rx: Receiver<WorkerCommand>,
    shutdown: Sender<()>,
    partition_manager: PartitionRuleManagerRef,
    node_manager: NodeManagerRef,
    catalog_manager: CatalogManagerRef,
    flow_notification_tx: FlowNotifier,
    worker_idle_timeout: Duration,
    flush_policy: TimingFlushPolicy,
    flush_limiter: FlushLimiter,
)