Remove patterns and nsd-control reconfig/repattern

[wtoorop]

If patterns are used in zones from the zone.list and those patterns are removed from the config and a nsd-control reconfig or repattern is done, a dangling reference remains with the zones that were added with those patterns.

[wtoorop]

It is fine if patterns are removed that do not have zones on zone.list though.
Similarly it is fine for a catalog-producer-zone: option to be removed or changed if there are no member zones configured with that pattern.