Revert "Stage 1 to support multiple domains"

This reverts commit 5e941cb055b1e3a1b625958ba57769c3f810777c.

.env.sample

@@ -1,8 +1,6 @@
 TYPE=mailman3
 
 DOMAIN=mailman3.example.com
-#EXTRA_DOMAINS=', `www.mailman3.example.com`'
-
 LETS_ENCRYPT_ENV=production
 
 SERVE_FROM_DOMAIN=${DOMAIN}

compose.yml

@@ -98,7 +98,7 @@ services:
       labels:
         - "traefik.enable=true"
         - "traefik.http.services.${STACK_NAME}.loadbalancer.server.port=80"
-        - "traefik.http.routers.${STACK_NAME}.rule=Host(`${DOMAIN}`${EXTRA_DOMAINS})"
+        - "traefik.http.routers.${STACK_NAME}.rule=Host(`${DOMAIN}`)"
         - "traefik.http.routers.${STACK_NAME}.entrypoints=web-secure"
         - "traefik.http.routers.${STACK_NAME}.tls.certresolver=${LETS_ENCRYPT_ENV}"
         - "coop-cloud.${STACK_NAME}.version=0.1.0+1.21.1"