fix: usr: Glues from different parent are rejected

The changes making BIND 9 parent-centric !11621 introduced an issue where it could be possible, when processing a referral, to use the glue to a nameserver which has a different parent than the zonecut. For instance:

	AUTHORITY
	test.example.		NS	ns.test.example.
	test.example.		NS	ns.foo.example.
	test.example.		NS	ns.bar.

	ADDITIONAL
	ns.bar.			A	1.2.3.4
	ns.foo.example.		A	5.6.7.8
	ns.test.example.	A	9.8.7.6

In such situation, only the glues for `ns.foo.example.` and `ns.test.example.` should be used, and the glue from `ns.bar.` must be ignored as this is not either a sub-domain or a sibling domain, the parent is different (`bar.` instead of `example.`). This is now fixed.

Sibling glue and cyclic sibling glues are defined in RFC 9471 section 2.2 and section 2.3.

Merge branch 'colin/cyclic-glues-test' into 'main'

See merge request isc-projects/bind9!11873