Replace variables for features.yml

For #1906 (closed)

The following discussion from !9668 (merged) should be addressed:

• @marcia started a discussion: (+2 comments)
  • Marcia: @axil, do you think I should change all this references from gitlab_ce: etc to gitlab_libre: etc?
  • Axil: I think we should, yes, to be consistent and finally learn the new lingo!