Autoscroll doesn't work if the scroll position in previously used chat is set and left not at the bottom of the page

[VolhaBazhkova]

1. Create a chat with several questions/answers to have scroll
2. Move the scroll at the top of the chat
3. Create new chat and send a message to receive any big answer, e.g. "Type 50 the most popular places to visit. Describe them. Numerate."
4. Note that when scroll appears, it doesn't move to the bottom of the chat -> bug autoscroll doesn't work

Note: in the 3rd step you may just create [Replay]chat -> Start replay -> autoscroll doesn't work.
Note: need to test carefully the same case but with "Regenerate" button. In this case user can read the answer above => we don't need to autoscroll.

501.mp4

Expected result: autoscroll should work with no dependencies on the position left in previous chat
See also #500

[VolhaBazhkova]

Move the ticket to developer as the fix doesn't work on staging.

[VolhaBazhkova]

Verified on MAC laptop (Safari), Windows laptop (Chrome, Edge, FF, Opera), iOS devices (iPhone, iPad), Android successfully.
Please note two new issues reported #926 #927