[Enhancement] Upgrade jetcd-core to 0.7.7

### Search before asking

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

### Enhancement Request

Dependabot failed to upgrade io.etcd:jetcd-core from 0.3.0 to 0.8.2 in https://github.com/apache/eventmesh/pull/4957.

As far as our existing CI process is concerned, the last available version is 0.7.x. To use 0.8.x, we would have to compile the etcd module separately and then bring it in via SPI. So we can upgrade to 0.7.7 first.

However, the CI fails with version 0.7.7, probably because there are references to deprecated APIs in our source code.

### Describe the solution you'd like

Update deprecated usages.

### Are you willing to submit PR?

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

### Code of Conduct

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

Start with the failed Dependabot upgrade in pull request 4957 and the CI output for jetcd-core 0.7.7. Inspect the etcd module for deprecated API usages and update them so the dependency upgrade completes successfully and the existing CI passes.

Written by the indexing model from the issue text.