[Ejabberd, Postfix, Dovecot] Do not run DNS check against unbound

data/Dockerfiles/ejabberd/docker-entrypoint.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 set -e
 
-until dig +short mailcow.email @unbound > /dev/null; do
+until dig +short mailcow.email > /dev/null; do
   echo "Waiting for DNS..."
   sleep 1
 done