Remove reconciling of artifacts during repo reconciliation

[jhrozek]

Summary

The GitHub API doesn't allow us to list packages for repos, only for
organizations. We tried to work around that by listing packages for the
org and then filtering by the repository attribute, but this does not scale well.

Moreover, we agreed that going forward we'd like to register and enroll
packages in a similar way that we do register and enroll repositories.

Fixes: #4618

Change Type

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

just made sure that repo register works.

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.