Fix weird culling of fluid interior top planes

[muzikbike]

Request Description

Build the following structure:

Now enter it in Spectator mode:

You'll notice something strange pretty quickly - the top faces of the water are visible from outside (as they should be, as they aren't coplanar with the ceiling and therefore hidden), but are completely invisible from the inside.

Things get even weirder if you knock out one of the corner blocks - one of the planes will be visible, whereas the other will not, separated by an abrupt cutoff at the block edge.

Here's another setup demonstrating much the same issue:

This is vanilla bug https://bugs.mojang.com/browse/MC-81654. May be within the scope of Sodium to fix - this is game graphics being weird and unintuitive, after all.