Bump verison to 7.19.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v7.18.1...de81b9845397ef114cdefda42f81beed4057cd07

• Release notes:

### Other changes (CI, backstage)

- !829 Reconfigure GitLab docker image to be able to use non-production EE_LICENSE

• Checklist before merging:

  • Diff link is up-to-date.
  • Based on the diff, lib/gitlab/qa/version.rb is updated, according to SemVer.
  • Release notes are accurate.

• Checklist after merging:

  • Update the release notes for the newly created tag.