Update CI to reasonable versions and fix resulting issues

This is basically the same as prometheus!4 (merged).

While at it, I also included a small optimisation in the apt role (run apt update only once at the end and not for every repository change).

Sieht nicht schlecht aus, aber das Klima hat 240 Issues mit dem Zustand?

mentioned in merge request databases!10 (merged)

approved this merge request

resolved all threads

merged

mentioned in merge request client!11 (merged)