@Override
    public void onDataNodeDelete(String instanceName) {
      handleDataNodeDelete(instanceName);
    }
@param dcName the name of data center or the cluster this handler is associated with.
@param helixClusterName the name of helix cluster which hosts the Ambry topology information.
@param onInitializationFailure callback to be called if initialization fails in a listener call.
@param isAggregatedViewHandler indicates if this clusterChangeHandler is a listener for changes in the entire
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HelixClusterManager.java