chg: dev: Skip in-domain nameservers that have no glue

A referral that names a nameserver inside the delegated zone but
provides no address for it leaves the resolver unable to reach that
server. named now logs "missing mandatory glue for <name>" at notice
level and skips the nameserver.

Merge branch 'ondrej/dont-store-missing-in-domain-glue-ns' into 'main'

See merge request isc-projects/bind9!11971