fix: usr: Stop caching lack of EDNS support

fix: usr: Stop caching lack of EDNS support

`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