[9.20] fix: dev: Reduce the false sharing the dns_qpcache and dns_qpzone

Instead of having many node_lock_count * sizeof(<member>) arrays, pack all
the members into a qpcache_bucket_t that is cacheline aligned to prevent
false sharing between RWLocks.

Backport of MR !10072

Merge branch 'backport-ondrej/prevent-nodelock-false-sharing-9.20' into 'bind-9.20'

See merge request isc-projects/bind9!10074