Remove itemstack mutation on player drop method

[Owen1212055]

This appears to cause alot of issues, as the general assumption when calling this method is that the itemstack would not be mutated.

Common issues that this seems to cause is item related actions that later increment a statistic, which is no longer true because the item type changes since its now considered empty. The dupe that this was meant to resolve was patched.

Fixes #11520 Fixes #11765 Supercedes https://github.com/PaperMC/Paper/pull/11521