Non-bipedal creatures should *not* use spellcast equip/unequip animations

Reverse of #5054 (closed).
The text keys unused in vanilla are really not intended to be used. Atronachs use iffy-looking segments of their casting animations. There might be other problems asset creators might not expect from merely testing vanilla. This could be changed when the character controller is dehardcoded, but for now, let's be conservative.