Enchanting table buttons and level icons render translucent pixels as opaque

More loosely relates to these issues: MC-144009 MC-145821 MC-164001 MC-165403

The bug

If the button textures and level icon textures for use in an enchanting table contain translucent pixels, these will be rendered fully opaque in-game.

How to reproduce

1. Download and apply the attached resource pack
2. Use an enchanting table

Expected results

To be able to see through the buttons (I've included the fixed UI texture from MC-268376).

Actual results

Opaque buttons.