Remove requirement of identity field in the request for TURN. (Azure#…

…15966)

* Remove requirement of identity field in the request.

* Update PR

* Address comment

specification/communication/data-plane/NetworkTraversal/preview/2021-06-21-preview/CommunicationNetworkTraversal.json

@@ -26,7 +26,6 @@
           {
             "in": "body",
             "name": "body",
-            "required": true,
             "schema": {
               "$ref": "#/definitions/CommunicationRelayConfigurationRequest"
             }
@@ -57,9 +56,6 @@
   "definitions": {
     "CommunicationRelayConfigurationRequest": {
       "description": "Request for a CommunicationRelayConfiguration.",
-      "required": [
-        "id"
-      ],
       "type": "object",
       "properties": {
         "id": {