The buildkit_config setting does not exist in the plugin-docker-buildx build
we run: the binary has no PLUGIN_BUILDKIT_CONFIG, so the block was dead YAML
and `docker buildx create` ran without --config. The plugin only writes a
buildkit.toml (pointing at /etc/docker/certs.d/<registry>/ca.crt) when
`registry` is set, which is why the tag build pushed fine and the PR build
had no CA. Set registry on every step and drop the dead block.
The matrix also overrode BASE_IMAGE with the Docker Hub path, so CI never
used the artifactapi remote that distro.env selects. Point it at artifactapi
and have ci/check-distros.sh fail when a matrix value restating a distro.env
key drifts from it.
unkin-agent