log that a zone is expired after setting the flag

log that a zone is expired after setting the flag

When a (secondary) zone is expired, the log message `<zone> expired` is
printed and the flag `DNS_ZONEFLG_EXPIRED` is set. Change the order by
setting the expired flag first, then printing the log.

This should fixes (rare but persistent) timing-related CI error when the
EDE 24 tests expect the zone to be expired (from the log) and
immediately after request and expect an EDE 24 error. (In some rare
cases, the server was still answering the response).