outage in gnt-fsn cluster (gitlab, collector, other services affected)

GitLab was not responsive this morning, and people also reported performance issues on collector.

Status site incident: https://status.torproject.org/issues/2023-12-06-gitlab-collector-outage/

Seems like this was an issue with the backend network that led to DRBD disk inconsistencies and I/O timeouts. The status-site update procedures without gitlab were tested and slightly updated.