Make SLES jobs run correctly on EE branches/tags

Different categories inside only clause of CI configuration are AND together. It becomes

(any of refs) AND (any of variables) AND (any of changes) AND (if kubernetes is active)

So, having $ee == "true" will cause anything where we don't explicitly set ee variable to fail the only clause, thus making the job not run. This is happening with our SLES jobs.

Unfortunately, for branch builds, we don't have a way out. We have to depend on support/is_gitlab_ee.sh script to check if it is an EE build or not.