resolve: remove RRs from zones before an update

During an update of RRs, the records of each DNS-SD service are
replaced with new ones. However the old RRs can only be removed from
the mDNS scopes as long as they remain accessible from the DnssdService
structures, otherwise they remain stuck there.

Therefore the removal must take place before the update.

(cherry picked from commit ee3713b7)
(cherry picked from commit 46ee05ed)
(cherry picked from commit 8082864e)