- Go back to using $MAJOR_VER instead of hard-coded version strings where
  possible.

- Default to 'auto' in NUMJOBS instead of just 1. Will make mysql-test-run
  faster.

- Unify autopkgtest with latest version in Debian, use eatmydata to make
  mysql-test-run faster.

- Salsa-CI: Remove obsolete 'artifacts: true' as that is the default value.

- Salsa-CI: Clean away obsolete temporary fixes.

- Salsa-CI: Unify with salsa-ci.yml in Debian, including test upgrades
  from Bullseye to Debian unstable.