Remove the "primary vertical" concept from the final join job

[jkoritzinsky]

Today, we have a "primary vertical" concept where we explicitly pull assets from Windows_x64 if they're present in multiple verticals.

We should instead make adjustments to how repos publish in the VMR so we don't publish duplicate assets with External visibility in the first place.

If possible, we should try to design this such that we can make adjustments to exactly which vertical publishes the rid-agnostic assets.