Remove EE-specific lines from Plan concerns
Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/6122.
Replaces https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7122 by building on https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7079.
Keep this WIP until it targets master (i.e. https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7079 is merged)
Edited by Lin Jen-Shin