scenario-tests is missing feed to sdk repository inside the VMR

[ViktorHofer]

scenario-tests.proj doesn't depend on "sdk" and hence doesn't get its feed. It reuses sdk's NuGet.config but that is missing an entry to sdk itself of course.

This is causing the build failures in the win-x64 vertical in an official build with unique versioning: https://dnceng.visualstudio.com/internal/_build/results?buildId=2627568&view=logs&j=9050e078-31bf-5111-d8ec-8b6fa95caf9c&t=71ed8226-4101-5eec-23b4-99befb5c82cb