Implement is_auto_partitioned method in table.rs

### Search before asking

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


### Description

See https://github.com/apache/fluss-rust/blob/1b265353f7329cbc83b50e443aa44288899d370e/crates/fluss/src/metadata/table.rs#L851

### Willingness to contribute

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