extract datasource's pool from metadatastore

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/incubator-kyuubi/issues?q=is%3Aissue) and found no similar issues.

### Describe the feature

extract datasource's pool from metadatastore

### Motivation

In the metadatastore module, it's connection is created from datasource pool which extracted to other class.
So, some other needs of using connecting to database can use the pool above-mentioned.
Such as providing MysqlGroupProvider in EngineRef

### Describe the solution

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

- [ ] Yes. I can submit a PR independently to improve.
- [x] Yes. I would be willing to submit a PR with guidance from the Kyuubi community to improve.
- [ ] No. I cannot submit a PR at this time.