Add post cleanup step for MacOS (#93126)
This goes together with https://github.com/pytorch/test-infra/pull/1548 to clean up MacOS M1 runner after the workflow finishes. I'm referring to my test branch here to test https://github.com/pytorch/test-infra/pull/1548. Once that PR is merged, I will switch to the main branch, i.e. `pytorch/test-infra/.github/actions/setup-miniconda@main` and `pytorch/test-infra/.github/actions/check-disk-space@main`
In the future, if there are more steps need to be done after MacOS workflow finishes, this can be also be refactored into a separate action like `teardown-linux`. There is only one step at the moment.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/93126
Approved by: https://github.com/ZainRizvi
