Clean up old scheduler archival task related services
This is dead code now as this has long been stopped and disabled in production.
Note: Also, it was probably not that well tested (and the coverage peek we have with this diff seems to approve)
Related to swh/infra/sysadm-environment#3782 (closed)
Test Plan
tox (should be happy)
Migrated from D6772 (view on Phabricator)