Fix release-1.11 push github action out of space issue. (#6500)

Signed-off-by: Xun Jiang <jxun@vmware.com>

.github/workflows/push.yml

@@ -64,6 +64,10 @@ jobs:
     - name: Publish container image
       if: github.repository == 'vmware-tanzu/velero'
       run: |
+        sudo swapoff -a
+        sudo rm -f /mnt/swapfile
+        docker image prune -a --force
+
         # Build and push Velero image to docker registry
         docker login -u ${{ secrets.DOCKER_USER }} -p ${{ secrets.DOCKER_PASSWORD }}
         VERSION=$(./hack/docker-push.sh | grep 'VERSION:' | awk -F: '{print $2}' | xargs)