Phantom have a Size NBT tag, despite they do not split like slimes

The bug

Despite you can uses the new /attribute commands to modify the mobs size, however, the phantom still have {{Size }}NBT tag, which is unused.

To reproduce

Summon a phantom with a large size /summon phantom ~ ~ ~ {Size:16}

×←It will have a large size, despite naturally spawned phantom are always 0 size.

Actual behavior

The phantom should not have an unused Size NBT tag.

Expect bahavior

The phantom have an unused {{Size }}NBT tag.