Wait before killing tail process for output
requested to merge tobias.ribizel/gitlab-ci-custom-executor-slurm-enroot_apptainer:wait_tail into main
This can otherwise lead to truncated output, see for example https://gitlab.com/ginkgo-project/ginkgo-public-ci/-/jobs/6110658110
Since the changes are visible to wait_until_file_contains, the running tail process should also pick up on them, unless extremely starved of compute time, or possibly inotify not firing