Add debug builds to Gitlab-CI
this allows to spot problems with tests that have different output in debug builds (see 392d388e)
Edited by Marco Clemencic
GitLab jobs artifacts no longer stored forever as of Monday, November 4th 08:30h. Further information under https://cern.ch/otg0152576
this allows to spot problems with tests that have different output in debug builds (see 392d388e)