Motivating discussion issue: https://discuss.elastic.co/t/arm-64-apm-attacher-images/359952

To use the APM attacher for Kubernetes (https://www.elastic.co/guide/en/apm/attacher/current/apm-attacher.html) on a k8s deployment on linux/arm64 -- which I'm guessing is an option on the managed k8s services (who wouldn't want to use Graviton, for example?) -- requires that the involved images support the linux/arm64 platform. As well the linux/amd64 platform support should remain.

This means multi-platform Docker images: https://docs.docker.com/build/building/multi-platform/
Which is straightforward in GH actions if already using the docker/build-push-action action, see https://docs.docker.com/build/ci/github-actions/multi-platform/

At the least we need this for the published docker.elastic.co/observability/apm-agent-nodejs image.
Likely we'll need it for the attacher image, docker.elastic.co/observability/apm-attacher, as well. I'm still following up on that.