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/MC-Utils.patch

@@ -4419,14 +4419,6 @@ diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
-@@ -0,0 +0,0 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
-     public final double[] recentTps = new double[ 3 ];
-     // Spigot end
-     public final io.papermc.paper.configuration.PaperConfigurations paperConfigurations; // Paper - add paper configuration files
-+    public static long currentTickLong = 0L; // Paper - track current tick as a long
- 
-     public static <S extends MinecraftServer> S spin(Function<Thread, S> serverFactory) {
-         AtomicReference<S> atomicreference = new AtomicReference();
 @@ -0,0 +0,0 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
              MinecraftServer.LOGGER.error("Failed to unlock level {}", this.storageSource.getLevelId(), ioexception1);
          }
@@ -4437,14 +4429,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          if (org.spigotmc.SpigotConfig.saveUserCacheOnStopOnly) {
              MinecraftServer.LOGGER.info("Saving usercache.json");
              this.getProfileCache().save();
-@@ -0,0 +0,0 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
-                     }
-                 }
-                 // Spigot start
-+                ++MinecraftServer.currentTickLong; // Paper - track current tick as a long
-                 if ( tickCount++ % MinecraftServer.SAMPLE_INTERVAL == 0 )
-                 {
-                     long curTime = Util.getMillis();
 @@ -0,0 +0,0 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
              MinecraftServer.LOGGER.debug("Autosave finished");
              SpigotTimings.worldSaveTimer.stopTiming(); // Spigot