The upstream woodpeckerci/plugin-docker-buildx image does not trust the
internal CA, so pushes/pulls against artifactapi.k8s.syd1.au.unkin.net
fail. Swap both the docker.yaml push step (docker-encapi) and the
build.yaml PR dry-run step to the custom CA-baked image published at
artifactapi.k8s.syd1.au.unkin.net/docker-internal/plugin-docker-buildx:latest.