[Feature] Support tcp client rebalancing so that the cluster can be expanded horizontally

### Search before asking

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

### Feature Request

I want the mesh to support client rebalancing so that the cluster can be expanded horizontally；

### Are you willing to submit PR?

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

The issue names no files, tests, or entry points. Start by locating the TCP client and cluster membership or balancing implementation, then determine the expected rebalancing behavior for horizontal expansion. Done should be defined by maintainers through tests or documented acceptance criteria for clients joining an expanded cluster.

Written by the indexing model from the issue text.