Reduce the number of outgoing queries

Reduce the number of outgoing queries

The dns_resolver mode of operation is to resolve all the domains as it
iterates the DNS tree to fill up the cache as quickly as possible.

This commit reduces the number of outgoing queries by reducing the
number of remote fetches started for the nameserver addresses resolution
via dns_adb_createfind() to a smaller number per depth of the recursion
since the delegation point (3 2 1 0) - where 0 means only create fetch
on demand if we don't have any addresses yet.