Update source-build subscriptions. (#531)
Update source-build subscriptions. (#531)

- Remove 3.0 -> master merge.  Master will likely diverge quite a bit from 3.0, and replacing it with a 3.1 -> master merge doesn't seem any better.
- Remove 2.1 -> 2.2 merge.  The only updates being made in 2.x are Version.Details.xml changes, which we never want to mirror anyway.
dagood/versions,dotnet/versions