This should avoid pointless reports to Sentry and Icinga on AdminShutdown
exceptions.
https://sentry.softwareheritage.org/share/issue/74f74880c807416988da16efa095be4a/
https://sentry.softwareheritage.org/share/issue/5796a55e3bb540b2ade33e4f52bc175b/
06:48:43 <+swhbot> icinga PROBLEM: service check_systemd on scrubber1.internal.softwareheritage.org is CRITICAL: SYSTEMD CRITICAL - swh-scrubber-checker-postgres@secondary-directory-0.service: failed, swh-scrubber-checker-postgres@secondary-directory-1.service: failed, swh-scrubber-checker-postgres@secondary-directory-2.service: failed, swh-scrubber-checker-postgres@secondary-directory-3.service: failed, swh-scrubber-checker-postgres@secondary-sn