Improve board fetch more in view trigger

[lucasbordeau]

Currently the in view trigger on boards are configured with a hard-coded value of 1600px margin from the root of the fetch more trigger component.

It was ok with a card that contains 5 fields but if a card contains more field we can scroll in a zone when in view is never triggered and skeleton show indefinitely.

We have to have a reliable system that triggers fetch more without having any stale UI state.