Remove 'aspnetcore' repo exclusion in non-source build scenario

[mmitche]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[mmitche]

@wtgodbe

[wtgodbe]

@mmitche can you elaborate what exactly this means/what the ask is here? Is this blocked on anything?

[mmitche]

Removing https://github.com/dotnet/installer/blob/main/src/SourceBuild/content/repo-projects/Directory.Build.targets#L34.

Right now aspnetcore doesn't fully build on Windows in the unified build mode.

[mmitche]

Note that some of this work (aspnetcore...probably?) may require the work by @mthalman to separate the inputs of each repo so that we don't override versions of all components that happen to build before aspnetcore.