Frostbites, zombie villagers and zombified piglins have the `FrostbiteConversionTime` tag

As the title says. Since these mobs cannot convert to frostbites, there is no reason for them to have the tag.

To reproduce

1. Summon a frostbite

2. /data get entity @n[type=frostbite] FrostbiteConversionTime
   ❌ The tag exists

3. Summon a zombie villager

4. /data get entity @n[type=zombie_villager] FrostbiteConversionTime
   ❌ The tag exists

5. Summon a zombified piglin

6. /data get entity @n[type=zombified_piglin] FrostbiteConversionTime
   ❌ The tag exists

Expected behavior

In none of these cases would the tag exist