Bump version to 5.10.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v5.9.0...5ea082a20d5cce5dd632e69944f34d766ec80066

• Release notes:

### New scenarios and scenario updates

- !398 Construct a Gitaly HA setup

### Fixes

- !449 Set default omnibus config in Praefect scenario

• 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:

  • Create a tag for the new release version.