Mannequin pose fall_flying incorrectly uses same pose as swimming

In version 1.21.9, the newly added "Player Model" entity (minecraft:mannequin) supports different poses via the pose field. However, it has been observed that when pose is set to fall_flying (elytra gliding), the model displays the exact same animation as swimming, rather than the expected elytra flying pose.

Steps to Reproduce:

1. Summon a mannequin entity using the following command:

   text

   /summon minecraft:mannequin ~ ~ ~ {pose:"fall_flying"}

2. Observe the model animation of this entity.

3. Summon another entity for comparison using:

   text

   /summon minecraft:mannequin ~ ~ ~ {pose:"swimming"}

4. Compare the animations of both entities — they are identical.