Remove live System.Text.Json reference from HostModel (#108263)

Author: ericstj

src/installer/managed/Microsoft.NET.HostModel/Microsoft.NET.HostModel.csproj

@@ -21,7 +21,8 @@
   <ItemGroup>
     <!-- SDK pins this to a lower version https://github.com/dotnet/sdk/issues/43325 -->
     <PackageReference Include="System.Reflection.Metadata" Version="$(SystemReflectionMetadataToolsetVersion)" />
-    <ProjectReference Include="$(LibrariesProjectRoot)System.Text.Json\src\System.Text.Json.csproj" />
+    <!-- The SDK distributes the live version of Json we can't reference that https://github.com/dotnet/runtime/issues/108262 -->
+    <PackageReference Include="System.Text.Json" Version="$(SystemTextJsonToolsetVersion)" />
   </ItemGroup>
 
   <ItemGroup>