KV tablet should not produce log via PRODUCE_LOG

### Search before asking

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

### Fluss version

main (development)

### Please describe the bug 🐞

Currently, when PRODUCE_LOG, we don't check whether a table is log table or pk table.

### Solution

_No response_

### Are you willing to submit a PR?

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

Start by tracing the PRODUCE_LOG handling in the Fluss codebase and identify where the table type is checked. Verify the behavior for KV (PK) tablets versus log tables, then add or update coverage so PRODUCE_LOG does not produce a log for a KV tablet.

Written by the indexing model from the issue text.