* In `event_queue.py`, only the sender and recipient users who have muted
the sender will have the "read" flag set.
* We already skip enqueueing notifications for users who've muted the sender
after 58da384da3.
* The queue consume functions for email and push notifications already
check filter messages which have been read before sending notifications.
* So, the "read" logic in `event_queue.py` is unnecessary, and the
processing power saved from not enqueueing notifications for a single
user should be insignificant, so we remove these checks all toghether.
10dd5f784b