Resolves issue causing edge case crash

[JoeStaff]

Fixes a crash caused by unsafe modification of killedEntityUUIDBlacklist in EntityDeathHandler, which could result in a NoSuchElementException during mob death events.

Root Cause

• isEntityBlacklisted() iterates over killedEntityUUIDBlacklist using a stream (creating an iterator).
• At the same time, cullEntityBlacklist() calls clear() on the same list.
• When multiple LivingDeathEvents fire in quick succession (e.g., automated mob killing), this leads to modification of the list while it is being iterated.
• This violates iterator safety and causes a crash: java.util.NoSuchElementException at java.util.AbstractList$Itr.next

Changes

Replaced stream-based lookup in isEntityBlacklisted() with a direct .contains() check:

• Avoids unnecessary iteration and allocation
• Improves performance and readability

Updated cullEntityBlacklist() to avoid unsafe in-place mutation:

• Replaces the list instead of clearing it while it may be in use

Issue is reproducible with rapidly killing mobs through automated means.

Test: ran high rate mob grinder (using mob-grinding-utils, roost, extra utilities) resulting in a mob kill every 1-3 ticks. Before fix, the game would crash every 1-3 hours. After fix, I've gone now well over 12 hours with no crash.