Don't import SkiaSharp.props into WindowsInteropTest.

Fixes the `"C:\Users\[user]\.nuget\packages\SkiaSharp\1.68.0\build\net45\SkiaSharp.dll.config" because it was not found.` error.

samples/interop/WindowsInteropTest/WindowsInteropTest.csproj

@@ -185,6 +185,5 @@
   </ItemGroup>
   <Import Project="..\..\..\build\Rx.props" />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
-  <Import Project="..\..\..\build\SkiaSharp.props" />
   <Import Project="..\..\..\build\LegacyProject.targets" />
-</Project>
+</Project>