fix product-service prod eureka port to 8821

prod/product-service-prod.properties

@@ -1,4 +1,4 @@
-eureka.client.service-url.defaultZone=http://discovery.rankin.com:8820/eureka/
+eureka.client.service-url.defaultZone=http://discovery.rankin.com:8821/eureka/
 
 # database setting
 spring.datasource.url=jdbc:mysql://rm-2zeptkzp761f34ch0.mysql.rds.aliyuncs.com:3306/rankin?useUnicode=true&characterEncoding=utf-8&autoReconnect=true&allowMultiQueries=true