Minecraft generates mipmapped textures for shields, but does not use them

Relates to: MC-276568 MC-277447 MC-277450 MC-277470 MC-277471 MC-277473 MC-277481

The bug

When loading the game's resources, Minecraft generates mipmapped textures for all shield-related textures. However, it does not use them at all, wasting game resources.

Since mipmapping only applies to blocks, meaning that items and entities do not use it, it is unclear as to why mipmapped versions are generated at all; I assume this is an oversight which persisted when the big atlas was split in 1.15 pre-release 1.

Steps to Reproduce:

1. Join a world

2. Press F3 + S to generate debug textures

3. Click the link posted in chat to go to your screenshots/debug folder

4. Find minecraft_textures_atlas_shield_patterns.png_0/1/2/3/4

How to fix

Don't generate these mipmapped textures for shields at all. Several other atlases (gui, map decorations, mob effects, paintings, particles) don't generate mipmapped versions of themselves, so why should shields.png-atlas if it's not going to be used?