[Improvement] cleanup shuffle server client when unregister shuffle

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/incubator-uniffle/issues?q=is%3Aissue) and found no similar issues.

### What would you like to be improved?

Cleanup shuffle server client when unregister shuffle.

### How should we improve?

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

No file, test, or entry point is named in the issue. Start by locating the unregister-shuffle flow and tracing the shuffle server client's lifecycle; done means the client is cleaned up when shuffle registration is removed, with the relevant behavior verified by tests.

Written by the indexing model from the issue text.