protected ConfigNodeHeartbeatHandler getConfigNodeHeartbeatHandler(int configNodeId) {
    return new ConfigNodeHeartbeatHandler(configNodeId, configManager.getLoadManager());
  }
Send heartbeat requests to all the Registered ConfigNodes.

@param registeredConfigNodes ConfigNodes that registered in cluster
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/load/service/HeartbeatService.java