[9.18] Implement reference count tracing for dns_catz_zone_t and dns_catz_zones_t
Partial backport of !7570 (merged).
The 2a52d306 commit is not backported, because in 9_18
the dns_catz_new_zones()
function can fail, so the old code makes more sense for this branch.
Edited by Arаm Sаrgsyаn