fix: 쿠키 domain 변경

- ec2 IP에서 그냥 오픈해버림 (개발용도)

Author: HYEONSIKOH

src/main/java/org/dfbf/soundlink/domain/user/service/UserService.java

@@ -49,7 +49,7 @@ public class UserService {
     private final TokenProperties tokenProperties;
     private final TokenService tokenService;
 
-    private final String domain = "43.203.98.65";
+    private final String domain = "";
 
     // 회원가입
     public ResponseResult signUp(UserSignUpDto userSignUpDto) {