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 Job ID Name Coverage
  Build
passed #105145
build-stable

00:05:14

passed #105144
build-unstable

00:05:34

failed #104987
build-stable

00:00:01

failed #104985
build-stable

00:00:01

failed #104986
build-unstable

00:00:01