Fix some CI rules to clean up the main branch pipelines a bit more
CI rule fixes following !5758 (merged):
- Run
ensure-generated-content-up-to-date
only in MR pipelines - Don't run
prepare-service-health-dashboard-json
onops.gitlab.net
- Make
deploy-dashboards
depend ontest-dashboards
- Fix
notify-mirror-source
to run again on main branch pipelines inops.gitlab.net
Part of https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/17505 and https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/16689
Edited by Pierre Guinoiseau