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/0640-Configurable-max-block-light-for-monster-spawning.patch

@@ -0,0 +1,19 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Nassim Jahnke <nassim@njahnke.dev>
+Date: Thu, 16 Dec 2021 09:40:39 +0100
+Subject: [PATCH] Configurable max block light for monster spawning
+
+
+diff --git a/src/main/java/net/minecraft/world/entity/monster/Monster.java b/src/main/java/net/minecraft/world/entity/monster/Monster.java
+index f73604d762efbac400d40f536ec1782fca584efa..e7bfce0534c7ef3a1480a1082ae8514caf78778b 100644
+--- a/src/main/java/net/minecraft/world/entity/monster/Monster.java
++++ b/src/main/java/net/minecraft/world/entity/monster/Monster.java
+@@ -91,7 +91,7 @@ public abstract class Monster extends PathfinderMob implements Enemy {
+             return false;
+         } else {
+             DimensionType dimensionType = world.dimensionType();
+-            int i = dimensionType.monsterSpawnBlockLightLimit();
++            int i = world.getLevel().paperConfig().entities.spawning.monsterSpawnMaxLightLevel.or(dimensionType.monsterSpawnBlockLightLimit()); // Paper - Configurable max block light for monster spawning
+             if (i < 15 && world.getBrightness(LightLayer.BLOCK, pos) > i) {
+                 return false;
+             } else {