Add integration tests for volo

Currently, we relies on the internal long-running stability testing services to ensure the stability of volo. This is not easily noticeable and cannot prevent errors from being merged in ci.

Thus, we need to add some integration tests for volo and run them in the github action.

I think we can just follow the guide in TRPL [here](https://doc.rust-lang.org/book/ch11-03-test-organization.html).

I'll add some examples later when I have time.

Start with the TRPL test-organization guide linked in the issue and inspect how volo's current stability testing services are used. Define integration-test coverage for volo and configure the GitHub Action to run it; done means the tests execute in CI and can prevent regressions from being merged.

Written by the indexing model from the issue text.