Geo - Calculate the checksum for outdated projects with less activity first

What does this MR do?

Order the Geo::RepositoryVerificationFinder#find_outdated_projects query bylast_repository_updated_at_asc to prioritize less active projects over high actives ones.

Why was this MR needed?

https://gitlab.com/gitlab-com/infrastructure/issues/3867#note_73032223

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• EE specific content should be in the top level /ee folder
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

https://gitlab.com/gitlab-com/infrastructure/issues/3867