Revert limitations on cloud customizability introduced in 25w16a

While snapshot 25w16a's introduction of endless clouds is a very welcome change, the associated flattening of cloud textures to rendering all pixels as a single color removes an element of customizability that resource packs (and, before them, texture packs) have had access to since (to my recollection) at least as early as Beta.

The removal of packmakers' ability to uniquely texture clouds, and especially to make use of semi-transparent pixels, limits an element of the game's customizability that's been present for at least a decade now. I'd very much like to see this customizability returned to resource packs, especially given that many packs have relied on it for years at this point.