HiveServer2 dynamic service discovery should let the JDBC client use default ZooKeeper namespace

Currently the client provides a url like:
jdbc:hive2://vgumashta.local:2181,vgumashta.local:2182,vgumashta.local:2183/;serviceDiscoveryMode=zooKeeper;zooKeeperNamespace=hiveserver2.
The zooKeeperNamespace param when not provided should use the default value.