Update gitlab-qa version to 10.3.0

• Diff: v10.2.2...2c542120

• Release notes:

### Other changes (CI, backstage)

- !1153 Add Selenoid grid setup.

• 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.

• Checklist after gitlab-qa version has been released by the post merge pipeline:

  • In the pipeline-common project, update the GITLAB_QA_VERSION and create a release.
  • In the GitLab project, update the ref for pipeline-common for package-and-test and review-apps.
  • Unless already done by renovate-gitlab-bot, or if you need it sooner, in the GitLab project, update the gitlab-qa gem version and Gemfile.lock (for an example, see: gitlab!117054 (merged)).