[Feature] Automatically detect changes to the expiration policy.

### Search before asking

- [x] I searched in the [issues](https://github.com/apache/paimon/issues) and found nothing similar.

### Motivation

After modifying the snapshot expiration policy, a restart of the writer or compactor job is required for the new configuration to take effect. This process is inconvenient, and it would be better if the system could automatically detect configuration changes.

### Solution

detect configuration changes when expire snapshot.

### Anything else?

_No response_

### Are you willing to submit a PR?

- [x] I'm willing to submit a PR!

Start at the snapshot-expiration path described as "expire snapshot" and inspect how the expiration policy is loaded and reused after configuration changes. Done means a running writer or compactor applies a modified policy without requiring a restart; add or update tests for that behavior if the repository provides them.

Written by the indexing model from the issue text.