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/0275-Async-command-map-building.patch

@@ -53,10 +53,10 @@ index 72756ef14b8ec8afd80313b9f6aaf76722cb18cf..a05aea8561ac102476ee1b3068942b09
          event.getPlayer().getServer().getPluginManager().callEvent(event);
  
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 0b266d3855723752d7789340f5d98ea106a97722..bd882ebb8e24de671518bf6b12f9ee4bc3f35128 100644
+index 699191356a9d873fa6bbe04ea3e5db91eb2db41d..8ecfd7a3daa99dabe796d28d27790fb8b45c628b 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
-@@ -931,6 +931,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
+@@ -930,6 +930,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
          }
  
          MinecraftServer.LOGGER.info("Stopping server");