fix: usr: Ignore updates removing DNSKEY RRset with class ANY

When a Dynamic Update is received that removes the ``DNSKEY`` (or ``CDNSKEY``,
or ``CDS``) RRset, remove all records except the ones that are in use
for signing for the zone.

Closes #6045

Merge branch '6045-dns-update-delete-in-use-dnskey-any' into 'main'

See merge request isc-projects/bind9!12166