Time-out jobs when GitHub fails to send a status update

I have observed a situation where a runner completes a job, but slurmactiond is not notified of the job's completion and it sticks around in the overview indefinitely. This can be remedied by a) timing out jobs after x minutex when their runner has finished or b) by timing out any job after, say, 24 hours.

Start by tracing how slurmactiond receives GitHub job status updates and retains completed jobs in the overview. Confirm the failure case where a runner finishes without a completion notification; done when jobs are reliably removed or timed out according to an agreed timeout policy.

Written by the indexing model from the issue text.