codeSplitters checks: queued runs nobody picks up stay queued #490

Follow-up to #465, waiting on the runner (#463).

With where set to here or both, a commit to main or a branch push queues a test run for a runner. Until #463 lands nothing picks it up, and later on a runner that's offline leaves runs queued forever too, which shows as "waiting" on the merge gate.

Wanted: the hourly cron cancels queued runs older than some limit, logging "no runner picked it up". The runner also decides which checks a repo has, instead of the single test run.