[OPPRO-277]Add free diskspace step before running velox testing

[weiting-chen]

What changes were proposed in this pull request?

Add free disk space step before running testing.

How was this patch tested?

No test, must check during GHA testing.

[github-actions[bot]]

Thanks for opening a pull request!

Could you open an issue for this pull request on Github Issues?

https://github.com/oap-project/gluten/issues

Then could you also rename commit message and pull request title in the following format?

[Gluten-${ISSUES_ID}] ${detailed message}

See also:

• Other pull requests

[FelixYBW]

Can we merge it now?

[FelixYBW]

@weiting-chen can we close the PR?

[jinchengchenghh]

Now we use docker to execute CI, so this PR is not needed.