Fixup Antares zip generation in some way (7.0)

- [x] This issue is blocking Antares generation for 7.0 previews.
- [ ] This issue is causing unreasonable pain

Antares zip generation is done using the -internal zips right now. This broke because aspnetcore moved the -internal zips to be non-shipping, and the generation only downloads the shipping zips. This broke for 7.0. This leaves us with 4 options:
- Have aspnet switch these back to shipping.
- Download the non-shipping files (inefficient) for generation
- Don't use the -internal zips to generate the antares artifacts (just extract the right directories from shipping zips)
- Have antares consume the actual shipping artifacts (shipping SDK, runtime and/or aspnetcore zips, but probably just the SDK since it contains all the files).

I am not a fan of the first or second options. The internal zips aren't meant for public consumption. The third option is okay, but non-ideal. Ideally, the -internal archives would go away altogether (4th option). Benefits:
- Antares consumes a truly supported layout that is hard to break because it's the same layout that all customers use.
- We get to get rid of the -internal archives, which only serve antares and inter-repo transport today. They're just another waste of space and time.