Update docfx.json

Remove ms.workload, which is unused metadata.

https://github.com/MicrosoftDocs/azure-docs-pr/blob/main/docfx.json#L1099
 
      "ms.workload": {
        "articles/cloud-shell/**/*.md": "infrastructure-services"
      },

Author: JasonWHowell

docfx.json

@@ -1096,9 +1096,6 @@
         "articles/cosmos-db/sql/*.md": "cosmosdb-sql",
         "articles/defender-for-iot/device-builders/*.md": "device-builders"
       },
-      "ms.workload": {
-        "articles/cloud-shell/**/*.md": "infrastructure-services"
-      },
       "monikerRange": {
         "articles/iot-edge/**/*.md": ">=iotedge-1.4",
         "articles/ai-services/document-intelligence/**/*.md": ">=doc-intel-2.1.0",