Update GitLab Pages to v0.8.1 (v10.7)

What does this MR do?

Updates GitLab Pages to v0.8.1 to fix a range of regressions introduced by the upgrade of GitLab Pages to v0.8.0

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

The list of changes can be found here: gitlab-pages#130 (closed)

This MR targets 10-7-stable directly because master is already at 0.9.0. I'll create a separate MR upgrading master to v0.9.1 (currently hypothetical)

Why was this MR needed?

Get pages working again in a range of environments

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/45639

Related to gitlab-pages#130 (closed)