pull-updates: check CI_COMMIT_BRANCH for passing --backports or --proposed-updates to apertis-pkg-pull-updates
Previously, apertis-pkg-pull-updates pulled by default versions from backports or proposed-updates repositories. Since it was more confusing than heplful because not part of our usual workflow, these repo are now optional. This change allows to control which repo needs to be checked by running the job on a 'debian/-backports' or 'debian/-proposed-updates' branch.
Depends on pkg/apertis-dev-tools!67 (merged)