build pacxx even in the samples ci

and stop rebuilding whenever any of the other repos build's successfully, instead just do nightly builds

This supercedes #24 (closed)

• build PACXX in pacxx-samples (pacxx-samples!27)
• stop triggering rebuilds
  • https://zivgitlab.uni-muenster.de/HPC2SE-Project/pacxx-llvm2
    • ci-main.yml (pacxx-llvm2!8)
    • project CI variables
    • pacxx-docker trigger definition
  • Update reference ci-main.yml from pacxx-llvm2 (!66 (merged))
  • https://zivgitlab.uni-muenster.de/HPC2SE-Project/pacxx-rv2
    • ci-main.yml (pacxx-rv2!7)
    • project CI variables
    • pacxx-docker trigger definition
  • https://zivgitlab.uni-muenster.de/HPC2SE-Project/pacxx-runtime
    • ci-main.yml (pacxx-runtime!37)
    • project CI variables
    • pacxx-docker trigger definition
  • https://zivgitlab.uni-muenster.de/HPC2SE-Project/pacxx-clang
    • ci-main.yml (pacxx-clang!5)
    • project CI variables
    • pacxx-docker trigger definition
  • https://zivgitlab.uni-muenster.de/HPC2SE-Project/pacxx-samples
    • ci-main.yml (pacxx-samples!28)
    • project CI variables
    • pacxx-docker trigger definition
• enable nightly rebuild in pacxx-docker