Builld Debian packages on GitLabCI

Next step will be to link this to gitlab testing which I started in another feature branch

I setup a spare VM of mine to be runner, that seems to help. Before I sometimes had to wait a bit before the build would start.

Latest run is https://gitlab.com/aegir/provision/pipelines/7066425

Another improvement could come from using a custom docker image that already has our dependencies ... http://stackoverflow.com/questions/34820755/gitlab-docker-executor-cache...

I set my runner to be in 'privileged mode', see https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/blob/master/docs/ex...

I thought this was needed when I saw warnings like:

We trust you have received the usual lecture from the local System     [warning]
Administrator. It usually boils down to these three things:            [warning]
                                                                       [warning]
    #1) Respect the privacy of others.                                 [warning]
    #2) Think before you type.                                         [warning]
    #3) With great power comes great responsibility.                   [warning]
                                                                       [warning]
sudo: no tty present and no askpass program specified                  [warning]
Changed permissions of                                                 [success]

But it turned out that a build could also pass with these warnings. see https://gitlab.com/aegir/provision/pipelines/7079376

One strange thing is that with the last build I had to retry the debian install twice to get it to pass .... not sure what the variation element is.

This is OK now ... packages are automatically pushed to the new repo ... temp name debian2.aegirproject.org I'll probably switch that to live today.

Follow-up for stable packages #2868586: Build stable Debian packages on GitLab CI