The example in the Playground can't be scrolled

[LidiyaGeorgieva]

Issue Description

No scrolling of the sample possible (the whole page is scrolled and the third notifications group is not fully visible)

Issue Type

• [ ] Documentation is unclear
• [ ] Documentation is incorrect
• [ ] Documentation is missing
• [X] Other

Steps to reproduce:

1. Open https://sap.github.io/ui5-webcomponents/nightly/components/fiori/NotificationList/#notification-list-with-group-items
2. Click on "Open in Playground" button
3. Expand the two collapsed groups
4. Issue: no scrolling of the sample possible (the whole page is scrolled and the third notifications group is not fully visible)