Add stale issue workflow for flaky test reports

[Mamaduka]

Fixes #37968

What?

PR adds a new workflow to check issues with the "[Type] Flaky Test" label and no activity in the past 30 days. Detected issues will be labeled "Stale" and closed in one day without activity.

Why?

I think it's safe to assume that the flaky tests report with no activity in the past 30 days might be resolved or was a false report due to some specific conditions.

Testing Instructions

The GitHub workflows are a bit hard to test, so verify settings based on the actions/stale docs - https://github.com/actions/stale/tree/v3.0.17#readme.

[talldan]

Thanks for putting this together - I've marked the PR as closing issue #37968.

There was some discussion before about not doing this because some flakey tests are skipped and still need to be fixed, so the issue will become stale and closed but the test will never be fixed.

But I think the volume is so much now that it's worth doing this anyway.

[Mamaduka]

Thanks, @talldan. Somehow I missed that issue.

There was some discussion before about not doing this because some flakey tests are skipped and still need to be fixed, so the issue will become stale and closed but the test will never be fixed.

Maybe we can prevent this by using the exempt-issue-labels option. I'm unsure if we already have a label that can be used for it or need to introduce a new one.

[talldan]

Maybe we can prevent this by using the exempt-issue-labels option. I'm unsure if we already have a label that can be used for it or need to introduce a new one.

Sounds like a good idea, it might be tricky to get contributors to understand the workflow, but worth trying. Maybe the stale or flaky messages can explain it.

[Mamaduka]

Also, considering that skipped tests require manual action, this might not be a big problem.

I will merge workflow in the current state but keep an eye out for improvements.