CI: Sync GitHub Actions config with master as of commit 240efcb

[kinkie]

Test staged commits using our docker images from Jenkins tests.
The added tests (see slow.yaml) were easier to adopt; we are also
working on enabling GitHub Actions for FreeBSD and some other images.

We do not run these added tests for PR commits because existing Ubuntu
tests (defined in quick.yaml) already expose the vast majority of build
problems, and we are worried that running a lot more tests for each PR
push event would consume too much GitHub resources and significantly
increase noise in PR checks summary, obscuring often-easier-to-handle
failures detected by quick.yaml tests.

CI: Sync GitHub Actions config with master as of commit 240efcb

---

Backported all v7 GitHub Actions changes as of master commit 240efcb,
except those related to master-specific CodeQL and MacOS tests.

[kinkie]

Current test run: https://github.com/kinkie/squid/actions/runs/11620947046

[kinkie]

Looks good, thanks for the help with the wording @rousskov . As the test run completes without error, I'll merge and focus on freebsd, ccache, other architectures, and finally decommissioning jenkins

[rousskov]

thanks for the help with the wording

FWIW, my suggestion contained the entire commit message (i.e. PR title and the entire PR description). The current PR title and description (except for the footer) are, IMO, still misleading.

[kinkie]

thanks for the help with the wording

FWIW, my suggestion contained the entire commit message (i.e. PR title and the entire PR description). The current PR title and description (except for the footer) are, IMO, still misleading.

Got you. Tweaked the wording some more with your input. I'm happy to land it now.

[rousskov]

Got you. Tweaked the wording some more with your input.

Sigh. PR description got arguably worse. PR title has not changed at all.

[kinkie]

ooh, that was the title you suggested using? It wasn't clear to me. I can amend it

[rousskov]

Alex: my suggestion contained the entire commit message (i.e. PR title and the entire PR description). The current PR title and description (except for the footer) are, IMO, still misleading.

Francesco: ooh, that was the title you suggested using? It wasn't clear to me.

Yes, when I say "title", I mean "title". When I say "entire commit message", I mean that too!

I can amend it

Please do not. It is not possible to amend a commit without force pushing. Please do not force-push official branches except in truly exceptional catastrophic events! This is not one of them.

You can amend PR title/description, of course, but the whole discussion is about commit message (that has been already formed based on then-current PR title/description). There is no need to amend PR title/description now IMO.