Sometimes pipelines fail with "unable to upgrade to tcp, received 409"
I've seen this a few times already in these days, mostly when we run a lot of pipelines in a row.
ERROR: Job failed (system failure): unable to upgrade to tcp, received 409 (exec.go:70:2s)
E.g., https://gitlab.torproject.org/tpo/applications/tor-browser/-/jobs/815307
/cc @brizental