fix(AlertGroupDemo): crashed when adding default alerts (#9826)

Author: MariaAga

packages/react-core/src/demos/examples/AlertGroup/AlertGroupToastWithNotificationDrawer.tsx

@@ -39,7 +39,7 @@ import { DashboardWrapper } from '@patternfly/react-core/src/demos/DashboardWrap
 interface NotificationProps {
   title: string;
   srTitle: string;
-  variant: 'default' | 'success' | 'danger' | 'warning' | 'info';
+  variant: 'custom' | 'success' | 'danger' | 'warning' | 'info';
   key: React.Key;
   timestamp: string;
   description: string;
@@ -345,8 +345,8 @@ export const AlertGroupToastWithNotificationDrawer: React.FunctionComponent = ()
         <Button variant="secondary" onClick={() => addNewNotification('warning')} style={alertButtonStyle}>
           Add toast warning alert
         </Button>
-        <Button variant="secondary" onClick={() => addNewNotification('default')} style={alertButtonStyle}>
-          Add toast default alert
+        <Button variant="secondary" onClick={() => addNewNotification('custom')} style={alertButtonStyle}>
+          Add toast custom alert
         </Button>
       </PageSection>