#31560 Add repo parameter to gitaly:install and workhorse:install

What does this MR do?

Add a repo parameter to the gitlab:workhose:install and gitlab:gitaly:install rake tasks, like the one for gitlab:shell:install

If not given, the default repository is still used.

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

Why was this MR needed?

In order to be able to install gitlab-workhorse and/or gitaly from mirrors if there is no (or unreliable) network connection to gitlab.com

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
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #31560 (closed)