The metrics endpoint was the only thing this bridge ever routed through
Traefik. With it gone, the container was still labeled `traefik.enable=true`
without defining any router, which makes Traefik fall back to its default
rule and produce a router pointing at nothing. It was also joining the
reverse-proxy network for no reason.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/5487