Stop strong-naming the Microsoft.Xaml.Behaviors.dll using the Behaviors.snk. The released NuGets always use FinalPublicKey.snk, so make sure to use that always.
Renamed src/Behaviors.snk to Tests/UnitTests.snk so it's less confusing
Updated UnitTests.csproj to use the newly named UnitTests.snk
Removed properties that only affected UnitTests.csproj from the Directory.Build.props