Only run cleanup jobs in MRs
Changes introduced
Only run the clean CI job in merge requests.
This should solve the issue where in MRs only the final CI job is run and one has to navigate back to see the actual pipeline. e.g. !1694 (merged) and many others
Tests
clean job does not run in the branch:
https://gitlab.cern.ch/atlas-physics/pmg/mcjoboptions/-/pipelines/3692861
It runs in the MR
Issues resolved
Closes #