Follow up of T7502: Kleopatra: Import secret key dialog improvement, see https://dev.gnupg.org/T7502#214891 and https://dev.gnupg.org/T7502#214964

When one imports a secret key without the G (group) flag and answers the question "Are you the only user?" with "No, others also use this key", we know that it is intended for usage in a group anyway.

So instead of the dialog "You have imported a new certificate (public key)" we want the "You have imported a shared secret key" dialog.

To be discussed: Can we use the text like it is now or do we need to change it so that it fits this case (importing a key without primary secret key but secret subkeys which was not explicitly created as a team key)?