RepoLookup should load metadata from database

Created by: keegancsmith

Since all code hosts are synced with upstream metadata included (#2025 (closed)), we can answer RepoLookup queries by speaking to our own database. This removes the need to speak to an upstream code host API on user requests. Additionally we can remove a lot of our application caching logic in code host clients.

This can only be done once we have migrated all code hosts.