handleShutdown() {
    debug(
      "Cluster-wide shutdown request received from node %s",
      this.remoteNodeId,
    );
    global.kuzzle.log.error(
      `[CLUSTER] Cluster wide shutdown from ${this.remoteNodeId}`,
    );
    global.kuzzle.shutdown();
  }
Handles cluster-wide shutdown
@return {void}