The --disable_yb_load_balancing_policy sample apps flag is not working

[mbautin]

As @robertpang noticed, we have this code

  protected void setupLoadBalancingPolicy(Cluster.Builder builder) {
    if (appConfig.localDc != null && !appConfig.localDc.isEmpty()) {
      builder.withLoadBalancingPolicy(new PartitionAwarePolicy(
              DCAwareRoundRobinPolicy.builder()
                      .withLocalDc(appConfig.localDc)
                      .withUsedHostsPerRemoteDc(Integer.MAX_VALUE)
                      .allowRemoteDCsForLocalConsistencyLevel()
                      .build()));
    } else if (!appConfig.disableYBLoadBalancingPolicy) {
      builder.withLoadBalancingPolicy(
              new PartitionAwarePolicy());
    }
  }

in AppBase.java, but in case none of the if branches are being hit (i.e. when --disable_yb_load_balancing_policy is specified on the command line) the custom YB Cassandra Java driver is actually using our PartitionAwarePolicy by default. Therefore to implement --disable_yb_load_balancing_policy correctly, we need to specify the default Cassandra load balancing policy explicitly in the above function.