Arcade does not respect NuGet's global packages folder setting

I have NuGet's global packages folder set to a location on a dev drive, via `dotnet nuget config set globalPackagesFolder s:\.nuget\packages`, which writes the setting to my user profile nuget.config. When I run build.cmd in this repo, packages are restored to c:\users\zivkan\.nuget\packages.

This causes me minor issues because the dotnet/sdk repo has the same problem. I built some custom nupkgs, then I modified the sdk repo's nuget.config to add my nupkg directory as a package source, and set the global packages folder so my custom packages wouldn't pollute my real global pacakges folder. However, the packages were not restored to the location I specified.