Auto-configure Flink Datalake Tiering Service from Fluss cluster instead of manual user specification

### Search before asking

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

### Motivation

https://github.com/apache/fluss/pull/1426#issuecomment-3138442642

Currently, users must manually set:
```plaintext
--datalake.format paimon
--datalake.paimon.metastore filesystem
--datalake.paimon.warehouse /tmp/paimon
```

These parameters are already configured in `server.yml`.

### Solution

Fetch parameters directly from Fluss cluster, or add validation for user parameter consistency.

### Anything else?

_No response_

### Willingness to contribute

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

Start with the server.yml settings and the handling of --datalake.format, --datalake.paimon.metastore, and --datalake.paimon.warehouse. Trace how the Flink Datalake Tiering Service receives these values and compare the alternatives of fetching them from the Fluss cluster or validating user-supplied values. Done means manual configuration is removed or inconsistent parameters are clearly rejected.

Written by the indexing model from the issue text.