chg: dev: Revert NTA flush on expire

Flushing the name when NTA expires causes problems for the ongoing
resolving process. Do not flush the name from the cache. Instead,
the resolver should do the flushing (this is planned to be implemented
later).

Merge branch 'aram/revert-nta-flush-on-expire' into 'main'

See merge request isc-projects/bind9!11765