#b19dcac2 improved the serializer so it sends default notification
levels to users to work around cases where a category edit would
would result in clients being left with invalid notification state
Unfortunately this did not address the root issue.
When we edit categories we publish state to multiple users this
means that the serializer is executed unscoped with no user.
The client already handles this case per:
https://github.com/discourse/discourse/blob/dcad720a4ce0aa67e94299ff8370fafd20cc41b2/app/assets/javascripts/discourse/app/models/site.js#L119-L119
If a property is not shipped to it, it will leave it alone on the
existing category.
This fix ensures that these wide category info updates do not
include notification state to avoid corruption of local state.
Sam Saffron
2987901043