Pass credentials in the current UGI while creating Tez session

The credentials present in the current UGI i.e. UserGroupInformation.getCurrentUser().getCredentials() isn't passed to the Tez session. It is instantiated with null credentials.

session = TezClient.create("HIVE-" + sessionId, tezConfig, true,
commonLocalResources, null);

In this case, tokens added using hive execution hooks, aren't available to Tez even if they are available in memory.