Items held by pandas unexpectedly use the "ground" display type

Relates to MC-276763 and MC-276801.

The bug

Items displayed when held by pandas use the "ground" display type, which is unexpected as said items are a considerable distance off the ground.

How to reproduce

A resource pack is attached to this ticket.

1. Download and apply the attached resource pack

2. /summon minecraft:panda ~ ~ ~ {HandItems:[{id:"minecraft:basalt", Count:1b},{}]}

3. Drop basalt on the ground

Expected results

It would appear huge on the ground, but not when held by a panda.

Actual results

It appears huge regardless of whether it's on the ground or held by a panda.

How to fix

Items held by pandas would either use an existing display type which makes more sense, or would have a new, dedicated display type which would be customizable independently.