Piglins' equipped items on the body and saddle slots are not dropped according to `drop_chances` when converting to zombified piglins

Since it was requested that MC-311623 be split up, this report covers equipment transfer when a piglin converts to a zombified piglin.

When such a conversion occurs, the zombified piglin retains any body or saddle or item given to the piglin via commands. Per the standard outlined in MC-311623, it would be expected that the items a zombified piglin cannot make use of (body and saddle) would be dropped according to drop_chances (preferably reflecting the chance value exactly), while the remaining items (hands, armor) would be retained by the zombified piglin (as currently happens).

This “bug” has basically no impact on the game, so I would not really mind if this were to be designated Works As Intended, Won’t Fix or Invalid. However, should other equipment transfer be fully implemented according to the MC-311623 standard, the reason for the inconsistency may be difficult to describe.

To reproduce

1. Be in the overworld

2. /summon minecraft:piglin ~ ~ ~ {TimeInOverworld:280,equipment:{mainhand:{id:crossbow},head:{id:golden_helmet},saddle:{id:saddle}},drop_chances:{mainhand:2f,head:2f,saddle:2f}}

3. Once the piglin converts, /data get entity @n[type=minecraft:zombified_piglin] equipment
   ✅ The crossbow has been retained per MC-172121
   ✅ The helmet has been retained
   ❌ The saddle has been retained

Expected behavior

The saddle would be dropped on the ground since the zombified piglin cannot make use of it.