fix: dev: do not inline dns_zone_gethooktable

Since !10959 `dns_zone_gethooktable()` is only called once per query,
and the suspicion (from perflab analysis) that this (simple, as just
returning a pointer) call was slowing things down (perhaps because of
code locality reasons?) doesn't matter anymore. So even if !10959
inlined it, it shouldn't matter anymore.

Merge branch 'colin/minimize-hooktable-lookup-followup' into 'main'

See merge request isc-projects/bind9!10962