chg: dev: Squash the qpcache tree and nsec tries

The dns_qpcache already had all the namespace changes needed to put the
normal data and auxiliary NSEC data into a single tree.  Remove the
extra nsec QP trie and use the single QP trie for all the cache data.

Merge branch 'ondrej/use-qp-namespace-in-cache' into 'main'

See merge request isc-projects/bind9!10975