Fix asset manifest generation (#10370)

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2056346

I made a mistake when I originally authored this, but we didn't notice
because we were shipping .NET Framework services so there were files at
the specified location too. Now that we've removed those, this started
to cause exceptions.

eng/targets/ReplaceServiceHubAssetsInVsixManifest.targets

@@ -3,16 +3,16 @@
 <Project>
   <Import Project="GenerateServiceHubConfigurationFiles.targets" />
   <!--
-    Injects generated Asset entries for ServiceHub configuration files to vsixmanifest:    
+    Injects generated Asset entries for ServiceHub configuration files to vsixmanifest:
       <Asset Type="Microsoft.ServiceHub.Service" d:Source="File" Path="{service-name}.servicehub.service.json"/>
   -->
-  
+
   <Target Name="GetGeneratedVsixManifestPath">
     <PropertyGroup>
       <_GeneratedVsixManifestPath>$(IntermediateOutputPath)source.extension.g.vsixmanifest</_GeneratedVsixManifestPath>
     </PropertyGroup>
   </Target>
-    
+
   <!--
     Redefines VSSDK target FindSourceVsixManifest to allow adding generated content to the manifest.
     Workaround for: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1179780
@@ -23,13 +23,13 @@
           Outputs="$(_GeneratedVsixManifestPath)">
     <PropertyGroup>
       <_Placeholder><![CDATA[<!--#SERVICEHUB_ASSETS#-->]]></_Placeholder>
-      <_Replacement>@(ServiceHubServiceJsonFile->'&lt;Asset Type="Microsoft.ServiceHub.Service" d:Source="File" Path="%(FileName)%(Extension)" /&gt;', '
+      <_Replacement>@(ServiceHubServiceJsonFile->'&lt;Asset Type="Microsoft.ServiceHub.Service" d:Source="File" Path="ServiceHubCore\%(FileName)%(Extension)" /&gt;', '
     ')</_Replacement>
     </PropertyGroup>
-    
+
     <Copy SourceFiles="$(VsixSourceManifestPath)" DestinationFiles="$(_GeneratedVsixManifestPath)" />
 
-    <WriteLinesToFile 
+    <WriteLinesToFile
       File="$(_GeneratedVsixManifestPath)"
       Lines="$([System.IO.File]::ReadAllText('$(_GeneratedVsixManifestPath)').Replace('$(_Placeholder)', '$(_Replacement)'))"
       Overwrite="true"