[9.18] fix: usr: Recently expired records could be returned with timestamp in future

Under rare circumstances, the RRSet that expired at the time of
the query could be returned with TTL far in the future.  This
has been fixed.

As a side-effect, the expiration time of expired RRSets are no
longer printed out in the cache dump.

Closes #5094

Backport of MR !10048

Merge branch 'backport-5094-fix-timestamp-in-ttl-9.18' into 'bind-9.18'

See merge request isc-projects/bind9!10060