Remove wall-time / unused skip tick protection (#11412)

Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.

patches/server/0781-Add-Sneaking-API-for-Entities.patch

@@ -1,29 +0,0 @@
-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: dawon <dawon@dawon.eu>
-Date: Wed, 19 Oct 2022 23:31:53 +0200
-Subject: [PATCH] Add Sneaking API for Entities
-
-
-diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
-index f950102a324d07aeba260bfa82fe88728f2362e5..ac513d3162a0794f226abc80bff21c799fe5802c 100644
---- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
-+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
-@@ -874,6 +874,18 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
-         return Pose.values()[this.getHandle().getPose().ordinal()];
-     }
- 
-+    // Paper start
-+    @Override
-+    public void setSneaking(boolean sneak) {
-+        this.getHandle().setShiftKeyDown(sneak);
-+    }
-+
-+    @Override
-+    public boolean isSneaking() {
-+        return this.getHandle().isShiftKeyDown();
-+    }
-+    // Paper end
-+
-     @Override
-     public SpawnCategory getSpawnCategory() {
-         return CraftSpawnCategory.toBukkit(this.getHandle().getType().getCategory());