[dns-forwarding] T1333: handle domain forward and general recursion in one configuration line

In the past we used the PowerDNS cofniguration option forward-zones and
forward-zones-recurse, but only the latter one sets the recursion bit in
the DNS query.

Thus all recursions have been moved to this config statement.

(cherry picked from commit 5886dd27cbc65f8cda04752bbd39a960b0887523)