Verify behavior of #427 after merge

#427 changes the PR-status steps, job timeout and Instantiate precompile of the two self-hosted Apple jobs in `ci-gpu-Apple.yaml` (macminim1, and macminim3 from #430). `issue_comment` workflows run from the default branch, so nothing in it executed before merge. Same situation as #416 and #417. This issue tracks the two checks that remain.

Any PR and one `Test this please` once #427 is on main: the two checks (`ci-gpu-Apple-M1 M1-JULIA1_12_3` and `ci-gpu-Apple-M3 M3-JULIA1_12_7`, as they appear on #429) go pending, then success or failure, and each Actions run finishes with the same state as its check. In the Instantiate log Metal should no longer appear under a `Precompiling packages...` header; its first compile should be the test step's `Precompiling for configuration --code-coverage=...` pass (both headers as in run 32264622892's log, where Metal compiled under each).

One run cancelled mid-test from the Actions tab: that job's check should land on `error` with description `job cancelled` (the step posts `job ${{ job.status }}`); before #427 it stayed "pending" forever. This is the half of #427 that was only checked as an expression before merge. If a cold build on either mini runs past 180 min the job will cancel itself and report the same way; that would be the signal to raise `timeout-minutes` or look at the machine rather than at the workflow.

Out of reach for both checks: a runner that loses its connection before any step runs, as both minis did on #429 on Sep 4. No step gets to post, so that check stays pending whatever the workflow says.

@williamfgc, can you fire the two? I can only read the logs afterward and I'll post what they show here. Closing once both come back clean.

After #427 is on main, trigger the two Apple workflows named in this issue with a PR and a `Test this please` comment. Inspect their checks and Actions logs, including the Instantiate and cancellation cases. Done means both checks and runs report matching final states, with Metal first compiling during the test step.

Written by the indexing model from the issue text.