Resolve "Follow-up from "Fix GITLAB_EDITION for gitlab ce""

What does this MR do?

Remove the CI variable GITLAB_EDITION=ce in review related CI jobs.

Previously the jobs have a set CI variable GITLAB_EDITION=ce which is then replaced with ee given the presence of ee/ directory.

Now that development is done on gitlab-org/gitlab with ee/ present, it is clearer to default to ee and override it to ce when ee/ directory is not present.

Closes #215151 (closed)