Zombified piglins remain leashed after being converted from leashed pigs

Summary
When a leashed pig turns into a zombified piglin after a lighting strike, the zombified piglin remains leashed, despite them being unleashable in Survival.

Steps to Reproduce

1. Use a lead on a pig.
2. Turn it into a zombified piglin with lightning strike.

Expected Result
The zombified piglin is not leashed.

Actual Result
The zombified piglin is leashed.