rem: usr: remove the secondary validator in query.c

Previously, when the additional section of a response was being
populated, if cached data was found with pending trust, it would be
opportunistically validated. The code implementing this validation was
not quite formally correct. Rather than fixing it, the code has been
removed: RRsets with pending trust are now omitted from responses.

Closes #5966

Closes #5968

Closes #5972

Merge branch 'each-remove-lightweight-validator' into 'main'

See merge request isc-projects/bind9!12236