Removes project reference between single vsmanproj and swixproj files.

Installer/Microsoft.VisualStudioTools.VSTestHost.vsmanproj

@@ -14,9 +14,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <ProjectReference Include="Microsoft.VisualStudioTools.VSTestHost.swixproj">
-      <Properties>VSTarget=$(VSTarget);Configuration=$(Configuration);Platform=$(Platform)</Properties>
-    </ProjectReference>
     <MergeManifest Include="$(OutputPath)Microsoft.VisualStudioTools*.json" />
   </ItemGroup>