Items held by dolphins use the "ground" display type

Relates to: MC-276801 MC-276802

The bug

Items displayed when held by dolphins reference the "ground" display type, despite them not being dropped items.

How to reproduce

A resource pack is attached to this ticket.

1. Download and apply the attached resource pack

2. /summon minecraft:dolphin ~ ~ ~ {NoAI:1,HandItems:[{id:"minecraft:basalt"}]}

3. Drop basalt on the ground

Expected results

Basalt would appear huge as a dropped item, but not when held by a dolphin.

Actual results

It still appears huge when held by a dolphin.

How to fix

Either make dolphins use a display type that makes more sense or introduce a dedicated one for dolphins.