Bump version to 7.27.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v7.26.0...2cf7a596eb6e9caaf44b8c91c5ef0ffbbb390b68

• Release notes:

### Fixes

- !937 Add retry to reconfigure method to avoid flaky failures
- !938 Seed admin token once in upgrade scenario

### Doc changes

- !933 Update docs where to find Jira credentials

### Other changes (CI, backstage)

- !929 Do not include screenshots for certain failures & fix blank stacktraces

• 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.