Remove ability to disable async chunks unless single core cpu

Too many people try to disable async chunks thinking its the cure
to some mysterious problem.

It is not possible to fully disable async chunks, and the portion
that this config controls is so minor in the grand scheme of things.

People are needlessly hurting their server following bad advice, so
just kill this config except for the people who might actually benefit from it.

Spigot-Server-Patches/0377-Asynchronous-chunk-IO-and-loading.patch

@@ -199,7 +199,7 @@ index af810987846efcd2bffbd23c31481b2d31c168dd..331493a172f58e71b464d635efdba461
                  doChunkInfo(sender, args);
                  break;
 diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
-index f9b1b198299166759fe0bd0a36d8d88c626e06a4..bf86444c479f346e7d56f10a7c0ebefd62f08f59 100644
+index f9b1b198299166759fe0bd0a36d8d88c626e06a4..f4a56028c21427d1164c5777285114a284b5643c 100644
 --- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
 +++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
 @@ -1,5 +1,6 @@
@@ -218,9 +218,7 @@ index f9b1b198299166759fe0bd0a36d8d88c626e06a4..bf86444c479f346e7d56f10a7c0ebefd
 +    private static void asyncChunks() {
 +        ConfigurationSection section;
 +        if (version < 15) {
-+            boolean enabled = config.getBoolean("settings.async-chunks", true);
 +            section = config.createSection("settings.async-chunks");
-+            section.set("enable", enabled);
 +            section.set("threads", -1);
 +        } else {
 +            section = config.getConfigurationSection("settings.async-chunks");
@@ -236,9 +234,9 @@ index f9b1b198299166759fe0bd0a36d8d88c626e06a4..bf86444c479f346e7d56f10a7c0ebefd
 +            section.set("load-threads", null);
 +        }
 +        section.set("generation", null);
++        section.set("enabled", null);
 +        section.set("thread-per-world-generation", null);
 +
-+        asyncChunks = getBoolean("settings.async-chunks.enable", true);
 +        int threads = getInt("settings.async-chunks.threads", -1);
 +        int cpus = Runtime.getRuntime().availableProcessors();
 +        if (threads <= 0) {
@@ -246,6 +244,8 @@ index f9b1b198299166759fe0bd0a36d8d88c626e06a4..bf86444c479f346e7d56f10a7c0ebefd
 +        }
 +        if (cpus == 1 && !Boolean.getBoolean("Paper.allowAsyncChunksSingleCore")) {
 +            asyncChunks = false;
++        } else {
++            asyncChunks = true;
 +        }
 +
 +        // Let Shared Host set some limits
@@ -3496,7 +3496,7 @@ index 24f3e8a6866bb416f04aca342514fa5dd3d314c8..2021c77c2cc832927de642d3542c3850
          return this.m;
      }
 diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
-index 62a0db6c08047be4ab28f5c23f4ae12694cf003f..70d3b429bfe08f1d2e5a3ac8368d8221770d5307 100644
+index 03ee383bfc3114a3be82d767d376bbf5f41bc5a7..0cba23c2c0880970dbb930caecb91bbc022cb52f 100644
 --- a/src/main/java/net/minecraft/server/PlayerConnection.java
 +++ b/src/main/java/net/minecraft/server/PlayerConnection.java
 @@ -544,6 +544,13 @@ public class PlayerConnection implements PacketListenerPlayIn {