[msbuild] remove Xamarin.Android.Tools.Versions.props (#253)

Context: dotnet/android@b1c2b33
Context: https://dev.azure.com/devdiv/DevDiv/_git/android-platform-support?path=/src/Xamarin.Installer.Build.Tasks/Xamarin.Installer.Common.props

This file was moved to a private repo that is now shared with IDEs.

Remove the file here to reduce confusion. It also is out of date, so
we don't want anything using it.

Author: jonathanpeppers

src/Xamarin.Android.Tools.AndroidSdk/Xamarin.Android.Tools.AndroidSdk.csproj

@@ -54,10 +54,4 @@
       <LastGenOutput>Resources.Designer.cs</LastGenOutput>
     </EmbeddedResource>
   </ItemGroup>
-
-  <ItemGroup>
-    <None Update="Xamarin.Android.Tools.Versions.props">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-    </None>
-  </ItemGroup>
 </Project>