Synchronize translation files

Author: @quba42 (quba42)

Redmine Issue: 8734, https://pulp.plan.io/issues/8734

This feature has been partially implemented, but I don't think it has ever actually worked and contains various sync breaking bugs.
As a result I will disable translation file synchronization completely for now.

The feature can then be re-added once fully completed. The following is a list of issues I have identified with the current incomplete implementation:

• Debian references extracted versions of translation file archives in the Release file even if not actually there. This messes with the current implementation, but can be fixed by handling translation files the same way we do this for package indices.
• We are currently synchronizing "translation diff file indexes", but not the files referenced from those indexes.
• We are storing translation files as GenericContent, but the corresponding serializer cannot deal with multi artifact content.

No files, tests, or entry points are identified. Start by locating the disabled translation file synchronization implementation and compare it with package-index handling; review Debian Release references, translation diff file indexes and referenced files, and GenericContent serialization. Done means synchronization is fully re-added without the listed breakages.