chg: usr: When forwarding, query with CD=0 first

Previously, when queries were forwarded to a remote resolver, the CD (checking disabled) bit was used, which could lead to bogus data being retrieved that might have been corrected if validation had been permitted. The CD bit is now only used as a fallback if an initial query without CD fails. See #5132.

Merge branch '5132-cd-retry' into 'main'

See merge request isc-projects/bind9!10024