ci: switch buildx back to docker driver to avoid pulling moby/buildkit from Docker Hub

The docker-container driver requires moby/buildkit:buildx-stable-1 from
Docker Hub, which is unreachable from the build network (EOF / timeout).
The docker driver runs buildkit inside the host daemon without needing
a separate container image.

Also explicitly rm + recreate the builder each run so stale
docker-container instances don't linger as the default.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Jenkinsfile

@@ -73,6 +73,16 @@ pipeline {
 
                     # Verify emulation works before proceeding
                     sudo docker run --rm --platform linux/arm64 docker.m.daocloud.io/library/alpine:latest uname -m
+
+                    # Use the default docker driver (not docker-container) so buildkit
+                    # runs inside the host daemon — no separate moby/buildkit container
+                    # needs to be pulled from Docker Hub.
+                    sudo docker buildx rm ${BUILDER_NAME} >/dev/null 2>&1 || true
+                    sudo docker buildx create \
+                      --name ${BUILDER_NAME} \
+                      --driver docker \
+                      --use
+                    sudo docker buildx inspect --builder ${BUILDER_NAME} --bootstrap >/dev/null
                 """
             }
         }