buildx ci: use docker github builder to build bin image and binaries

https://github.com/docker/github-builder-experimental/issues/21 closes #3005

Nov 13 '25 11:11 crazy-max

GitHub hosted runner doesn't have enough space to build our image: https://github.com/docker/buildx/actions/runs/19330419315/job/55292703625#step:8:521

#28 [linux/amd64->darwin/amd64 buildx-build 1/1] RUN --mount=type=bind,target=.   --mount=type=cache,target=/root/.cache   --mount=type=cache,target=/go/pkg/mod   --mount=type=bind,from=buildx-version,source=/buildx-version,target=/buildx-version <<EOT (set -e...)
#28 1051.0 k8s.io/api/autoscaling/v2beta1: mkdir /tmp/go-build135885827/b986/: no space left on device

Hence why we free up disk space currently (see https://github.com/docker/buildx/pull/3040)

For our reusable workflow, one way to fix it would be to distribute build across runners: https://github.com/docker/github-builder-experimental/issues/2

Nov 13 '25 13:11 crazy-max

Switch reusable workflow ref to bake-distrib https://github.com/docker/github-builder-experimental/pull/22 so builds are distributed across runners.

Nov 14 '25 12:11 crazy-max

Pushed extra commit to also build our binaries with our reusable workflow.

Nov 16 '25 10:11 crazy-max