[connman] dnsproxy: Prefer results with domain name while domain_append is true

If domain_append is set and forward_dns_reply() processes the response
for query without the domain name earlier than the response for one
with the domain name set we need to make sure that the response is
not sent back to the client if rcode and ancount are zero until the
last nameserver response is processed.

This solves the issues when client queries hostname which is a valid
domain tld, eg. com, bz, org.