[DRAFT] Improve Docker build speed in CI by building on macOS

[simu]

Checklist

• Keep pull requests small so they can be easily reviewed.
• Update the documentation.
• Update tests.
• Categorize the PR by setting a good title and adding one of the labels:
  bug, enhancement, documentation, change, breaking, dependency, internal
  as they show up in the changelog
• Link this PR to related issues.

[simu]

This was an experiment to see if we can build the container image on macOS with docker, however, the Docker CLI isn't installed on hosted macOS runners due to licensing issues, cf. https://github.com/orgs/community/discussions/25777#discussioncomment-3249229

The last CI run checks if we have podman on hosted macOS runners, but that binary doesn't seem to be preinstalled either: https://github.com/projectsyn/commodore/actions/runs/23286544039/job/67711310491?pr=1322