[flink] IT test for latest scan startup mode for changelog virtual table

### Search before asking

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


### Description

Refer this comment for more context:
https://github.com/apache/fluss/pull/2467#discussion_r2724324458

### Willingness to contribute

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