fix workflow: revert to original structure without caching

.github/workflows/docker_build_push.yml

@@ -16,37 +16,14 @@ jobs:
     - name: Checkout code
       uses: actions/checkout@v2
 
-    - name: Set up Docker Buildx
-      uses: docker/setup-buildx-action@v1
-
-    - name: Cache Docker layers
-      uses: actions/cache@v2
-      with:
-        path: /tmp/.buildx-cache
-        key: ${{ runner.os }}-buildx-${{ github.sha }}
-        restore-keys: |
-          ${{ runner.os }}-buildx-
-
     - name: Login to DockerHub
-      uses: docker/login-action@v1
-      with:
-        username: ${{ secrets.DOCKER_USERNAME }}
-        password: ${{ secrets.DOCKER_PASSWORD }}
+      run: echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
 
     - name: Build and push Docker image
-      uses: docker/build-push-action@v2
-      with:
-        context: ./backend
-        file: ./backend/Dockerfile
-        tags: ${{ secrets.DOCKER_USERNAME }}/haengsha-backend:latest
-        push: true
-        cache-from: type=local,src=/tmp/.buildx-cache
-        cache-to: type=local,dest=/tmp/.buildx-cache-new
-
-    - name: Move Docker cache
       run: |
-        rm -rf /tmp/.buildx-cache
-        mv /tmp/.buildx-cache-new /tmp/.buildx-cache
+        cd backend
+        docker build -t "${{ secrets.DOCKER_USERNAME }}/haengsha-backend:latest" .
+        docker push "${{ secrets.DOCKER_USERNAME }}/haengsha-backend:latest"
 
     - name: Deploy to EC2
       run: |