Remove improperly applied flattening extension. (Azure#763)

The x-ms-client-flatten extension has been applied in the wrong location.
Unfortunately fixing it would introduce a breaking change so instead we
will just remove the extension.

arm-resources/resources/2016-09-01/swagger/resources.json

@@ -1865,7 +1865,6 @@
     "DebugSetting": {
       "properties": {
         "detailLevel": {
-          "x-ms-client-flatten": true,
           "type": "string",
           "description": "Specifies the type of information to log for debugging. The permitted values are none, requestContent, responseContent, or both requestContent and responseContent separated by a comma. The default is none. When setting this value, carefully consider the type of information you are passing in during deployment. By logging information about the request or response, you could potentially expose sensitive data that is retrieved through the deployment operations."
         }