Fix Tez to reuse IPC connections

When tracking DAG progress, TezClientUtils ends up creating new remote user. Because of this new UGI creation, IPC connections are not reused internally.

https://github.com/apache/tez/blob/master/tez-api/src/main/java/org/apache/tez/client/TezClientUtils.java#L965

More info from Hadoop side:

In hadoop's IPC layer, connectionIds are checked based on UserGroupInformation.
https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java#L1600

However, UserGroupInformation comparison is based on ==
https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java#L1789