Remove/change "mark all as read" button in notification

## Use case/Reasoning

I have some priority notifications, saw two entries I did not care about and saw that "mark all as read" button.
I thought it would mark the two entries/notifications as read but instead it marked *all* notifications as read in the whole app in all directories.

This happened twice to me and I regret it totally.🙈

Because obviously I have a pile of feed entries that I have not yet read and did not want to cleanup.
I just expected/wanted to mark the ones mentioned in the notification as read/get rid of them.

Another problem/use case could be that one may accidentally press that button.

## Proposed solutions

* either remove that button. IMHO it does more harm than good.
* or at least make it only mark the mentioned articles in the notification and not all of them