Remove changes to old config file. New ejabberd package uses yml config.

Remove lines that would cause the script to fail with ejabberd >= 14.07-1.

With the new package, mod_http_bind is enabled by default.

I think https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=503313 is not really fixed yet, so there's no IPv6 by default. But I'll try to get that issue fixed in the ejabberd package instead of using a work-around here.