[Sprite] Fix Impidimp front, Arctozolt back variants

[Fontbane]

What are the changes the user will see?

• Fixes Arctozolt back variants not loading if the user has experimental sprites turned on for some reason
• Impidimp doesn't have an obvious problem atm, but better safe than sorry
• Fixes random different colored pixel on Arctozolt back (static, T0/T1)

Why am I making these changes?

• Part of issue [Sprite] Documenting Fix for variant desync between static and exp loading issue #5335
• If exp sprite uses shader json and static sprite uses separate sprites for variants, bad stuff happens
• If this occurs on a back sprite, it causes it not to load with exp sprites turned on, since (to my understanding) the game will try to look for a sprite for the exp back variants (which don't exist, a shader json does)

What are the changes from a developer perspective?

• Impidimp static front and Arctozolt static back variants now use shader json instead of custom sprites

Screenshots/Videos

Impidimp static front variants using shader json:


old sprites:

Arctozolt back exp before


After:

static before (separate sprites, weird pixel)




after (shader, fixed weird pixel)

How to test the changes?

Turn on the "dex for devs" setting and check in consistent and exp

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• Have I tested the changes manually?
• Are all unit tests still passing? (npm run test)
  • Have I created new automated tests (npm run create-test) or updated existing tests related to the PR's changes?
• Have I provided screenshots/videos of the changes (if applicable)?
  • Have I made sure that any UI change works for both UI themes (default and legacy)?

Are there any localization additions or changes? If so:

• Has a locales PR been created on the locales repo?
  • If so, please leave a link to it here:
• Has the translation team been contacted for proofreading/translation?