Follow consistent runner naming and tagging

https://zivgitlab.uni-muenster.de/HPC2SE-Project/compute-server-admin/issues/7

TODO:

• activate new runners
• fix .gitlab_ci.yml (!52 (merged))
• deactivate old runners
  • wait for !53 (merged) before that since that uses the old ones still
• test (https://gitlab.dune-project.org/joe/pacxx-docker/pipelines/12242)