void triggerInstanceConfigChangeNotification() {
    for (MockHelixAdmin helixAdmin : helixAdmins.values()) {
      helixAdmin.triggerInstanceConfigChangeNotification(false);
    }
  }
Trigger an InstanceConfig change notification for all datacenters.
ambry-clustermap/src/test/java/com/github/ambry/clustermap/MockHelixCluster.java