Bump version to 8.2.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v8.1.0...cfd14b6d6f2c13615b2ed4a296f9176c579d46bf

• Release notes:

### New scenarios and scenario updates

- !944 Add Omnibus config for metrics e2e tests

### Other changes (CI, backstage)

- !1008 New env var to control public IP detection

• 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.