chg: dev: Use default listening rules from config.c string

Remove special code which creates default listeners, and use the normal named.conf configuration parser instead. This removes unneeded code and makes the built-in configuration text provide a true primary source of defaults. This change should be transparent to end-users and should not cause any visible change.

Closes #1424

Merge branch '1424-listen-builtin-config' into 'main'

See merge request isc-projects/bind9!2663