Feat: Eureka defaultZone 변경

Author: Feedbaek

DiscoveryServer/src/main/resources/application.yml

@@ -9,6 +9,6 @@ spring:
 eureka:
   client:
     service-url:
-      defaultZone: ${EUREKA_SERVER_URL:http://localhost:8761/eureka/}
+      defaultZone: ${EUREKA_EXTERNAL_URL:http://localhost:8761/eureka/}
     register-with-eureka: false
     fetch-registry: false