Improve result reporting for the certificate refresh

For keyserver refresh show "not found" result also if more than one
key was updated but none was found on the keyserver.
For WKD refresh show "not found" result if no keys where found via WKD.

(cherry picked from commit aebfdc6f2e2eb1cf870725c87e402ca95ec614a2)

• GnuPG-bug-id: T7190