[ReleasePR streamanalytics] [Stream Analytics] Fix S360 for auto-scale feature (Azure#2562)

Create to sync Azure/azure-rest-api-specs#20090
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/main...azure-sdk:sdkAuto/streamanalytics?expand=1)

Author: msftbot[bot]

schemas/2021-10-01-preview/Microsoft.StreamAnalytics.json

@@ -62,6 +62,17 @@
             ]
           }
         },
+        "sku": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/Sku"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The properties that are associated with a SKU."
+        },
         "tags": {
           "oneOf": [
             {
@@ -3206,6 +3217,17 @@
     "Sku": {
       "type": "object",
       "properties": {
+        "capacity": {
+          "oneOf": [
+            {
+              "type": "integer"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The capacity of the SKU."
+        },
         "name": {
           "oneOf": [
             {