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/0368-Inventory-getHolder-method-without-block-snapshot.patch

@@ -0,0 +1,42 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Phoenix616 <mail@moep.tv>
+Date: Wed, 10 Jun 2020 23:55:15 +0100
+Subject: [PATCH] Inventory getHolder method without block snapshot
+
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java
+index 75eb794f796b31c0c5ef80a6d27a56711a522f5e..e824fe361286a5f41b137be92d799eef54ae4b87 100644
+--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java
++++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java
+@@ -543,6 +543,13 @@ public class CraftInventory implements Inventory {
+         return this.inventory.getOwner();
+     }
+ 
++    // Paper start - getHolder without snapshot
++    @Override
++    public InventoryHolder getHolder(boolean useSnapshot) {
++        return inventory instanceof net.minecraft.world.level.block.entity.BlockEntity ? ((net.minecraft.world.level.block.entity.BlockEntity) inventory).getOwner(useSnapshot) : getHolder();
++    }
++    // Paper end
++
+     @Override
+     public int getMaxStackSize() {
+         return this.inventory.getMaxStackSize();
+diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryDoubleChest.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryDoubleChest.java
+index c00c787a73b0796b645667427666b7ec4e333992..c3e2c9e2c3cbec2eda38096b6482bac1a0ea1dce 100644
+--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryDoubleChest.java
++++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryDoubleChest.java
+@@ -63,6 +63,13 @@ public class CraftInventoryDoubleChest extends CraftInventory implements DoubleC
+         return new DoubleChest(this);
+     }
+ 
++    // Paper start - getHolder without snapshot
++    @Override
++    public DoubleChest getHolder(boolean useSnapshot) {
++        return getHolder();
++    }
++    // Paper end
++
+     @Override
+     public Location getLocation() {
+         return this.getLeftSide().getLocation().add(this.getRightSide().getLocation()).multiply(0.5);