Some tweaks based on debugging https://gitlab.torproject.org/jnewsome/sponsor-61-sims/-/jobs/63872
Save resource monitoring to a log instead of dumping to the job's stdout, and don't tail logs on stdout. Now that we have a web shell on the runner, we can still check these while the job is running if needed. This should make it easier to follow the rest of the job log.
In the after_script, don't fail if the source
env file is missing. This wasn't the root cause of the failure in job 63872, but in general we should be defensive in the after_script so that we don't inadvertently skip other post-processing due to inconsequential failures.