Clean up "<Targets" for doing "dotnet restore" as they are no longer needed for 3.8.5+

[SimonDarksideJ]

Summary

Following Remove the RestoreContentCompiler as it was redundant., the "<Targets" for managing dotnet restore and dotnet tool restore is no longer required.

This section should be removed from all templates for the 3.8.5 release and beyond

  <Target Name="RestoreDotnetTools" BeforeTargets="CollectPackageReferences">
    <Message Text="Restoring dotnet tools (this might take a while depending on your internet speed and should only happen upon building your project for the first time, or after upgrading MonoGame, or clearing your nuget cache)" Importance="High" />
    <Exec Command="dotnet tool restore" />
  </Target>