Don't apply multiple enchantment glints for items with multiple texture layers

[muzikbike]

Request Description

This is a somewhat annoying vanilla bug that notably affects enchanted leather armour. The resource pack attached to https://bugs.mojang.com/browse/MC-166101 makes this issue more clear.

The expected result would be for the enchantment glint to cover the entire item, but only once - the intensity should be constant throughout, and said intensity should only be a single layer of the glint effect.

Here's the enchanted books from that ticket:

[jellysquid3]

Closing in favor of #2497 since the issues you have reported about enchantment glint are fundamentally the same problem.