Long motion: Fix jumping to end of a list and double scrollbars

Describe the bug
When navigating from a motion with long metadata (i.e. several polls) to a different menu, the browser remembers the scrolling position from the previous page.

How to Reproduce

1. enter a meeting that has >10 participants
2. create a motion and add at least 3 ended polls (analog is fine)
3. scroll to the end of the motion page
4. click on the another menu (you need several items in the list because the possibility for scrolling needs to be possible)
5. you jump to the end of the list of participants and you see two scrollbars (only in Chromium)

Expected behavior
When navigating to a menu from a long motion, then you should jump to the most upper place of the list and not where the scrollbar was saved

Additional info
This bug and its fix does not relate in any way to other saved scrolling behaviour, e.g. when you scroll down in the agenda, open an item and navigate back.

Start by reproducing the navigation flow in Chromium with a long motion, several ended polls, and a long participant list. Trace how scrolling is retained when switching menus and identify the source of the second scrollbar. Done means navigation opens the destination list at the top with one scrollbar, without changing the separate agenda scroll-back behavior.