Tidy / restructure CI configuartion
With the additions to the pipeline I'm working on, the configuration file becomes a bit unwieldy.
To clean up the configuration, one can use the images from https://git.physik.uni-wuerzburg.de/ALF/ALF_docker, which have all necessary dependencies preinstalled. With this, no invocation of the package manager is needed, which will also reduce job execution times.
Furthermore, one can generalize templates for different compilers.