There is now only one build-image, so we don't need to assign it a
number.

The Gitlab CI was having some issues with the double "$" which required
some further fixups after removing.

things are pretty similar to the drone file, but we don't seem to need
to build a special dind image for alpine, so we've removed that job.

Reviewed-on: https://gitea.pep.foundation/claudio/pEpLinuxSetupForThunderbird/pulls/4

There might be a better way, but this seems to work.

Accidentally introduced in 19d46a96.

Merge pull request 'Fix "user and system binaries are swapped" bug.' (#2) from msc-patch-2 into master

Reviewed-on: https://gitea.pep.foundation/claudio/pEpLinuxSetupForThunderbird/pulls/2

Reviewed-on: https://gitea.pep.foundation/claudio/pEpLinuxSetupForThunderbird/pulls/1