ci: Only run static analysis jobs on default branch
i.e. for commits on default branch and merge requests against default branch. Do not run these jobs for tags, it's pretty useless and would force us to distinguish between tags on default branch and tags on maintenance branches.
Do not run these jobs on translation commits either, since in this case the build jobs didn't run (unfortunately 'needs' doesn't handle this automatically).
Amends: 8bf2175d