Shut off MD module upgrades after 7.4 EOL

[andystaples]

Will need to be added as part of documentation work for #943 Backport to 7.2 required, will link to that PR once this one is merged and rebased

Pull request checklist

• [ ] My changes do not require documentation changes
  • [x] Otherwise: Documentation issue linked to PR
• [ ] My changes should not be added to the release notes for the next release
  • [x] Otherwise: I've added my notes to release_notes.md
• [ ] My changes do not need to be backported to a previous version
  • [x] Otherwise: Backport tracked by issue/PR #issue_or_pr
• [x] I have added all required tests (Unit tests, E2E tests)