fixed resource type definition for Microsoft.ApiManagement/service/ap…

…is/schemas (Azure#14769)

* fixed ApiManagement/service/apis/schemas

* updated schema/document definition

Co-authored-by: Alan Feng <alanfeng@microsoft.com>

specification/apimanagement/resource-manager/Microsoft.ApiManagement/preview/2021-01-01-preview/definitions.json

@@ -4986,16 +4986,7 @@
       "description": "API Schema create or update contract Properties."
     },
     "SchemaDocumentProperties": {
-      "properties": {
-        "value": {
-          "type": "string",
-          "description": "Json escaped string defining the document representing the Schema. Used for schemas other than Swagger/OpenAPI."
-        },
-        "definitions": {
-          "type": "object",
-          "description": "Types definitions. Used for Swagger/OpenAPI schemas only, null otherwise."
-        }
-      },
+      "type": "object",
       "description": "Schema Document Properties."
     },
     "SubscriptionCollection": {