[v9_18] Add Oracle Linux 9

This !6581 (merged) backport includes the following backports to satisfy system test requirements on Oracle Linux 9:

• !6306 (merged) - see the discussion on why (not) to backport this from June
• !6532 (merged)
• !6506 (merged) - a partial backport of; another partial backport has been done in !6533 (merged)