[MC-246257] The horns of some entities aren't mirrored

The Bug:

The horns of some entities aren't mirrored.

Below, I've constructed a table that highlights all of these errors. Please note that there may be more entities affected by this that aren't listed below.

Entity	Are their horns mirrored?	Notes	Screenshot Example
minecraft:cow	No	Can only be seen when using a 32-bit (or higher-quality) resource pack.	cow.png
minecraft:goat	No		goat.png
minecraft:mooshroom	No	Can only be seen when using a 32-bit (or higher-quality) resource pack.	mooshroom.png

Steps to Reproduce:

Download the attached resource pack (if necessary) to make testing this much easier. MC-246257.zip
Summon any of the entities listed above, for example, a goat.

/summon minecraft:goat ~ ~ ~ {NoAI:1b,Silent:1b}

Look at the entity's horns closely.
Take note as to whether or not the horns of some entities are mirrored.

Observed Behavior:

The horns aren't mirrored.

Expected Behavior:

The horns would be mirrored.