Remove ms.prod = xamarin. Replaced by ms.service = xamarin (#2118)

Co-authored-by: Docs Allowlist Management <docs-allowlist-mgmt@microsoft.com>

docs/en/docfx.json

@@ -39,6 +39,7 @@
       ]
     },
     "globalMetadata": {
+      "ms.service": "xamarin",
       "apiPlatform": "dotnet",
       "breadcrumb_path": "~/breadcrumb/toc.yml",
       "author": "dotnet-bot",
@@ -48,7 +49,6 @@
       "searchScope": ["Xamarin"],
       "uhfHeaderId": "MSDocsHeader-DotNet",
       "ms.topic": "managed-reference",
-      "ms.prod": "xamarin",
       "ms.technology":"xamarin-essentials",
       "feedback_system": "GitHub",      
       "feedback_product_url": "https://github.com/xamarin/Essentials/blob/main/PRODUCT-FEEDBACK.md"