Deduplicate transferred / moved repos

[kiskoza]

Description

It's pretty confusing on the landing page that it's full of duplicated repositories, e.g. in the attached screenshot

The code already had a Todo in place, and some of the issues / PRs mentioned code snippets used during repository cleanups, I put them into this PR.

Related Issue

https://github.com/codetriage/CodeTriage/issues/1704#issuecomment-1272840699 https://github.com/codetriage/CodeTriage/issues/824#issuecomment-499686203 https://github.com/codetriage/CodeTriage/issues/1791 (and a few others...)

Motivation and Context

It helps people find the right repository, for example mozilla/rust has 244 subscribers and rust-lang/rust has 308, though these two repos are the same.

How Has This Been Tested?

I updated the existing test suite.

Screenshots (if appropriate):

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.