fix(paper): prevent server stalls from inventory holder snapshots

[noctiro]

Summary

Prevent HeadDB's GUI holder checks from creating unnecessary block entity snapshots during inventory click and close events.

This behavior can be abused to cause a server-wide denial of service, potentially resulting in a watchdog-triggered shutdown.

Root cause

Normal container clicks pass through multiple HeadDB menu handlers, even when the player is not using a HeadDB menu.

These handlers call Inventory#getHolder() to identify custom menu holders. For block inventories, this creates a block entity snapshot, which serializes and deserializes the container contents. With deeply nested item data, this work can be expensive.