[AKS] remove maxPods default (#3178)

Author: mboersma

specification/containerservices/resource-manager/Microsoft.ContainerService/stable/2018-03-31/managedClusters.json

@@ -832,8 +832,7 @@
         "maxPods": {
           "type": "integer",
           "format": "int32",
-          "description": "Maximum number of pods that can run on a node.",
-          "default": 30
+          "description": "Maximum number of pods that can run on a node."
         },
         "osType": {
           "$ref": "#/definitions/OSType",