[Enhancement]: Scale number of log service per dn

### Is there an existing issue for enhancement?

- [X] I have checked the existing issues.

### What would you like to be added ?

```Markdown
Right now for DN we will have one raft group (3 replicas). We should
consider scale out number of raft groups per DN.

Not clear what is a good partition scheme. Maybe we hash on database
id.
```

### Why is this needed ?

For a powerful DN instance we do not want raft/log to become scale bottleneck.

If partition by db, potentially we have a faster recovery time if DN fails

### Additional information

_No response_