`named` could falsely learn that a server doesn't support EDNS when
a spoofed response was received; that subsequently prevented DNSSEC
lookups from being made. This has been fixed.
Closes https://gitlab.isc.org/isc-projects/bind9/-/issues/3949
Closes https://gitlab.isc.org/isc-projects/bind9/-/issues/5066
Merge branch '5066-stop-caching-lack-of-edns-support' into 'v9.21.7-release'
See merge request isc-private/bind9!776