net/traefik: Update to upstream version 2.9.4
Details:
- Update to 2.9.x branch: https://github.com/traefik/traefik/releases/tag/v2.9.4
- No breaking config changes, see https://doc.traefik.io/traefik/migration/v2/#v29
- but "Traefik Pilot" has been removed.
MFH: 2022Q4
(cherry picked from commit f7d27b2826592362278b4f99d92c0c8bd68dbeb9)