die alte syntax mit loop bei apt ist bald deprecated deswegen auch die
syntax angepasst.

todo aus ansible ergänzt

since mailcow now comes with a default ejabbered we need to deactivate
it. That means: use the exit container, alter the config so it doesn't
try to use the ports from our prosody. Finally set a alias on trhe nginx
because it won't start if it doesn't find it's ejabberd.

removed all comments
rechecked config with current (1.26.0) sample config