[pkg-apparmor] Bug#912723: apparmor-profiles-extra: Replace home-made GitLab CI with subscription to the Salsa pipeline

[intrigeri at debian.org]

Source: apparmor-profiles-extra
Version: 1.24
Severity: normal

A few months ago I've copied and adjusted the GitLab CI configuration
found in salsa-ci-team/pipeline. Since then, a better way was created
to handle this: one can now subscribe a package to the Salsa pipeline,
which will manage the GitLab CI config for us.

Advantages:

 - The shared config has been improved, allowing to run piuparts
   and reprotest.
 - No need to maintain our forked copy anymore.
 - Whatever improvements we do benefit everyone else, and vice-versa.

Next steps:

1. Wait for
   https://salsa.debian.org/salsa-ci-team/pipeline/merge_requests/36 to
   be merged.
2. Follow the instructions in
   https://salsa.debian.org/salsa-ci-team/pipeline/
3. Drop our current debian/.gitlab-ci.yml