Pick the right milestone and close for MRs

This is fixing #190 (comment 189633173)

• Pick the right milestone, which is just the first one!
• Close the merge request report as we do for issues
• I'll write a script to correct the issues/MRs based on the current reports:
  • https://gitlab.com/gitlab-org/gitlab-ce/issues/64290
  • https://gitlab.com/gitlab-org/gitlab-ce/issues/64291
  • https://gitlab.com/gitlab-org/gitlab-ee/issues/12709
  • https://gitlab.com/gitlab-org/gitlab-ee/issues/12710