Test doRollback

[jelly]

Coverage has uncovered that we don't cover:

     431           4 :     } else if (isRollback(info)) {
     432           7 :         action_name = "rollback";
     433           0 :         action = () => Dialogs.show(<ConfirmDeploymentChange actionName={action_name}
     434           0 :             bodyText={cockpit.format(_("System will rebase to $0, updated $1."), version, releaseTime)}
     435           0 :             onConfirmAction={() => doRollback(akey, info.osname.v)}
     436           0 :         />);

This needs research how realistic it is do achieve that.