[BE] merge conflict 해결 과정 중 중복 선언된 메서드 제거 #762

* refactor: 중복된 메서드 선언 제거

* test: 누락된 contextTest 추가

* test: git 설정 오류로 누락된 contextTest 추가

backend/src/main/java/harustudy/backend/auth/controller/AuthController.java

@@ -12,7 +12,6 @@
 import jakarta.servlet.http.HttpServletResponse;
 import java.util.Arrays;
 import lombok.RequiredArgsConstructor;
-import org.springframework.beans.factory.annotation.Value;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
@@ -58,13 +57,6 @@ public ResponseEntity<TokenResponse> refresh(
         return ResponseEntity.ok(tokenResponse);
     }
 
-    private Cookie setUpRefreshTokenCookie(TokenResponse tokenResponse) {
-        Cookie cookie = new Cookie("refreshToken", tokenResponse.refreshToken().toString());
-        cookie.setMaxAge(refreshTokenExpireLength.intValue() / 1000);
-        cookie.setPath("/");
-        return cookie;
-    }
-
     private String extractRefreshTokenFromCookie(HttpServletRequest request) {
         return Arrays.stream(request.getCookies())
                 .filter(cookie -> cookie.getName().equals("refreshToken"))