Delete InternalsVisibleTo that are no longer needed (#28444)

Author: jkotas

src/System.Reflection/ref/System.Reflection.Manual.cs

@@ -10,7 +10,6 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uap-Release|AnyCPU'" />
   <ItemGroup>
     <Compile Include="System.Reflection.cs" />
-    <Compile Include="System.Reflection.Manual.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\System.Runtime\ref\System.Runtime.csproj" />