Bump version to v8.10.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v8.9.0...37e57663accd8eb1938186ad1f4e5cff8731f44c

• Release notes:

### Fixes

- !1062 Populate chaos proxies via http call
- !1065 Login to docker registry for pipelines from omnibus-gitlab security mirror

• 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.