Support connecting with Kerberos-enabled ZooKeeper cluster

Now we can not connect with Kerberos-enabled ZooKeeper cluster for both online and offline components.

The following modules should be updated to support Kerberos-enabled ZooKeeper.

- TaskManager
- NameServer / Tablet

The issue mentions updating TaskManager, NameServer, and Tablet modules to support Kerberos authentication with ZooKeeper. Start by examining the existing connection logic in these components, likely in the source tree under nameserver/ and tablet/. Research how Kerberos is integrated with ZooKeeper client libraries in C++. 'Done' means the components can successfully authenticate and operate with a Kerberos-secured ZooKeeper cluster.

索引モデルが issue の本文から書いたものです。