@Override
  public HelixManager getZkHelixManagerAndConnect(String clusterName, String instanceName, InstanceType instanceType,
      String zkAddr, ClusterMapConfig clusterMapConfig) throws Exception {
    if (overrideGetHelixManager) {
      return mockHelixManager;
    }
    return super.getZkHelixManagerAndConnect(clusterName, instanceName, instanceType, zkAddr, clusterMapConfig);
  }
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