@Override
  public HelixManager getZKHelixManager(String clusterName, String instanceName, InstanceType instanceType,
      String zkAddr, ClusterMapConfig clusterMapConfig) {
    return getHelixManager(instanceType);
  }
Return the {@link MockHelixManager}
@param clusterName unused.
@param instanceName unused.
@param instanceType unused.
@param zkAddr unused.
@return the {@link MockHelixManager}
ambry-clustermap/src/test/java/com/github/ambry/clustermap/MockHelixManagerFactory.java