[Improvement] Supply more demo datasets for playground

### 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.

### What would you like to be improved?

I find some public small datasets

- https://kylin.apache.org/docs31/howto/sample_dataset.html
- https://www.briandunning.com/sample-data/

Other datasets are welcome, especially could be used to draw charts by BI tools.

### How should we improve?

_No response_

### Are you willing to submit PR?

- [ ] Yes. I can submit a PR independently to improve.
- [ ] 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.

No repository files, tests, or entry points are named. Review the linked sample-dataset sources and the playground's current dataset arrangement, then define which additional datasets are suitable for BI charting and how completion will be verified.

Written by the indexing model from the issue text.