change back vmss api-version to 2018-10-01 (#19474)

Author: XiaofeiCao

specification/network/resource-manager/readme.java.md

@@ -23,6 +23,14 @@ directive:
   - rename-operation:
       from: InboundSecurityRule_CreateOrUpdate
       to: InboundSecurityRuleOperation_CreateOrUpdate
+  - from: vmssNetworkInterface.json
+    where: '$.info'
+    transform: >
+      $["version"] = "2018-10-01";
+  - from: vmssNetworkPublicIpAddress.json
+    where: '$.info'
+    transform: >
+      $["version"] = "2018-10-01";
 ```
 
 ### Java multi-api