gitlab-ci: reference new docker location

* .gitlab-ci.yml: Here.
5 jobs for er/fixcommonlib in 5 minutes and 34 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed build-stable #105145

00:05:14

passed build-unstable #105144

00:05:34

failed build-stable #104987

00:00:01

failed build-stable #104985

00:00:01

failed build-unstable #104986

00:00:01