Region ticker disables before plugins, disallowing plugin cleanups in the world

Expected behavior

N/A

Observed/Actual behavior

The region ticker disables before plugins, preventing any further ticks while shutting down.

For some plugins, who spawn entities or block modifications in the world, normally they can run cleanups in onDisable(). However, because synchronous tasks on disable cannot be done due to the lack of main thread, they have to pend this task to RegionScheduler. Which is disabled at the time onDisable() occurs.

This means some plugins cannot run their cleanup, such as removing entities, reverting block changes, etc.

Steps/models to reproduce

1. Set a block in the world with a task
2. Set a task to revert that block change in onDisable()
3. Stop the server
4. The block will not be reverted

Plugin and Datapack List

BetterScoreboard, packetevents, PlaceholderAPI, ProjectKorra, ViaBackwards, ViaVersion

Folia version

1.21.4-DEV-master@8af1aef (2025-04-11T00:37:47Z) (Implementing API version 1.21.4-R0.1-SNAPSHOT)

Other

No response

Start by tracing the shutdown ordering for the region ticker, RegionScheduler, and plugin onDisable() lifecycle described in the issue. Reproduce the block-change cleanup scenario, then verify that plugin cleanup work can still be scheduled during shutdown and that the reverted block or removed entities are processed before the server stops.