Unleashing a mob in creative mode drops an unnecessary lead

The bug

When you unleash a mob, the lead will drop even if you do it in creative mode. The lead should not drop if you do it in creative mode. There is absolutely no reason for the lead to drop in creative mode.

How to reproduce:

1. Be in creative mode
2. Spawn a mob that can be leashed, such as a pig
3. Leash it
4. Unleash it

Observed result: The lead dropped as an item.

Expected result: The lead won't drop as an item.

You will also notice that the hand swing animation does not play, which is a different bug (MCPE-52105).