Force Plugins that use delayed tasks for init back in their place

Will now run those tasks just before we print "Done" so that startup
time is appropriately accounted for a plugin, as well as will no longer
trip the watchdog on startup.

Any plugin that tries to bypass this is just going to then trip watchdog
on Spigot too, so don't you dare.

Stop trying to cheat the delay your plugin added to startup time.

This isn't a behavior change because the first thing the tick does....
was run these tasks....

So it's just moving it slightly a few lines to be before a watchdog tick and
to account for it in "Done" time.

Fixes #3294

Spigot-Server-Patches/Improved-Watchdog-Support.patch

@@ -1,7 +1,9 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Aikar <aikar@aikar.co>
 Date: Sun, 12 Apr 2020 15:50:48 -0400
-Subject: [PATCH] Forced Watchdog Crash support and Improve Async Shutdown
+Subject: [PATCH] Improved Watchdog Support
+
+Forced Watchdog Crash support and Improve Async Shutdown
 
 If the request to shut down the server is received while we are in
 a watchdog hang, immediately treat it as a crash and begin the shutdown
@@ -35,6 +37,9 @@ We have to ensure Thread Death propagates correctly though to stop main complete
 
 This is to ensure that if main isn't truely stuck, it's not manipulating state we are trying to save.
 
+This also moves all plugins who register "delayed init" tasks to occur just before "Done" so they
+are properly accounted for and wont trip watchdog on init.
+
 diff --git a/src/main/java/net/minecraft/server/CrashReport.java b/src/main/java/net/minecraft/server/CrashReport.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/server/CrashReport.java
@@ -93,6 +98,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
      // CraftBukkit end
      // Spigot start
      public static final int TPS = 20;
+@@ -0,0 +0,0 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
+ 
+         this.server.enablePlugins(org.bukkit.plugin.PluginLoadOrder.POSTWORLD);
+         this.server.getPluginManager().callEvent(new ServerLoadEvent(ServerLoadEvent.LoadType.STARTUP));
++        this.server.getScheduler().mainThreadHeartbeat(this.ticks); // Paper - run all 1 tick delay tasks during init, this is going to be the first thing the tick process does anyways, just move it inside of "Done"  anything at 3+ won't be caught here but also will trip watchdog.... tasks are default scheduled at -1 + delay, and first tick will tick at 1
+         this.serverConnection.acceptConnections();
+         // CraftBukkit end
+ 
 @@ -0,0 +0,0 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
          // CraftBukkit start - prevent double stopping on multiple threads
          synchronized(stopLock) {