fix(traefik): restore --ping=true, causing the dashboard to vanish

Docker's provider drops a container's own docker-label routers when
Docker reports that container unhealthy. --ping=true had been dropped
somewhere along the way, so /ping 404'd, the healthcheck failed,
traefik was marked unhealthy, and its own traefik-dashboard-web(-secure)
routers disappeared as a result. Also restores acme.tlschallenge=true
(needed for cert renewal) and drops the debug log level used for
earlier troubleshooting.

traefik/compose.yml

@@ -5,7 +5,8 @@ services:
     command:
       - "--api.insecure=true"
       - "--api.dashboard=true"
-      - "--log.level=DEBUG"
+      - "--ping=true"
+      - "--log.level=INFO"
       - "--accesslog=true"
       - "--global.sendAnonymousUsage=false"
       - "--global.checkNewVersion=true"
@@ -21,6 +22,7 @@ services:
       - "--entrypoints.web.http.redirections.entryPoint.scheme=https"
       - "--entrypoints.web.http.redirections.entryPoint.permanent=true"
       - "--entrypoints.web-secure.http.middlewares=security-headers@file,fail2ban@file"
+      - "--certificatesresolvers.resolver.acme.tlschallenge=true"
       - "--certificatesresolvers.resolver.acme.email=${ACME_EMAIL}"
       - "--certificatesresolvers.resolver.acme.storage=/letsencrypt/acme.json"
       - "--experimental.plugins.fail2ban.moduleName=github.com/tomMoulard/fail2ban"