feat: test null hostkey on ci

Signed-off-by: Gauravsingh Sisodia <xaerru@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

tests/torture.h

@@ -80,6 +80,7 @@ struct torture_state {
     char *srv1_pidfile;
     char *srv1_config;
     bool srv_pam;
+    bool disable_hostkeys;
     char *srv_additional_config;
     struct {
         ssh_session session;