auth: remove the default default from the zone_id argument in lookup()

auth: remove the default default from the zone_id argument in lookup()

lookup calls without a zone_id:

modules/lmdbbackend/lmdbbackend.cc:  lookup(QType(QType::SOA), domain, -1);
pdns/communicator.hh:                b->lookup(QType(QType::ANY),name, -1);
pdns/pdnsutil.cc:                    B.lookup(QType(QType::NS), domain, -1);
pdns/pdnsutil.cc:                    B.lookup(QType(QType::A), DNSName(std::to_string(random()))+domain, -1);
pdns/pdnsutil.cc:                    B.lookup(QType(QType::DNSKEY), zone, -1 );
pdns/dnsbackend.cc:                  this->lookup(QType(QType::SOA),domain,-1);
pdns/mastercommunicator.cc:          B->lookup(QType(QType::NS), di.zone, -1);
pdns/ws-auth.cc:                     di.backend->lookup(QType(QType::ANY), qname, -1);
pdns/slavecommunicator.cc:           B->lookup(QType(QType::RRSIG), di.zone, -1);