Notifications menu should not display a scrollbar when the scroll is not needed

STEPS TO REPRODUCE

1. Login with a new user (which has no notifications in Notifications list yet)
2. Click on Notifications bell
3. Observe the menu
4. Login with an user which has a single notification in the list (or generate a single notification event with another user for him)
5. Observe the menu
6. Login with an user which has two notifications in the list (or generate yet another notification event with another user)
7. Observe the menu

EXPECTED RESULTS

As there are no notifications available, the scrollbar is not displayed on the Notifications list.

This is valid also when there are only a few events in the list and scroll is not needed (on my browser, Edge 81, the scrollbar became active when the list reached 7 events).

ACTUAL RESULTS

The scrollbar (even if it's grayed out) is displayed even when there are no notifications available in the list as well as when the list contains a few notifications and scroll is not needed. This also might affect user experience when using notifications feature.

The issue could not be reproduced on XWiki 9.9.