Use GitLab Pages v0.4.1

What does this MR do?

Switches to GitLab Pages v0.4.1, fixing a long-standing bug for projects with multiple custom domains

Are there points in the code the reviewer needs to double check?

The only change in Pages is https://gitlab.com/gitlab-org/gitlab-pages/merge_requests/27

Why was this MR needed?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests
  • All builds are passing
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-pages/merge_requests/27 https://gitlab.com/gitlab-org/gitlab-pages/merge_requests/26 https://gitlab.com/gitlab-com/support-forum/issues/1740