refactor: 테스트를 위한 조건 복원

Author: kkiseug

.github/workflows/backend-prod-cd.yml

@@ -1,7 +1,7 @@
 name: Backend Prod Server CD
 
 on:
-  pull_request:
+  push:
     branches: [ main ]
     paths:
       - 'backend/**'
@@ -100,4 +100,3 @@ jobs:
             echo "❌ 배포 실패! 서버가 동작하지 않습니다."
             sudo docker logs coursepick-backend --tail 50
             exit 1
-