Remove no longer needed undead horse leash patch

This is now default vanilla behavior

Fixes #3644

Spigot-Server-Patches/0221-ItemStack-getMaxItemUseDuration.patch

@@ -0,0 +1,37 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Tue, 5 Jun 2018 23:00:29 -0400
+Subject: [PATCH] ItemStack#getMaxItemUseDuration
+
+Allows you to determine how long it takes to use a usable/consumable item
+
+diff --git a/src/main/java/net/minecraft/server/ItemStack.java b/src/main/java/net/minecraft/server/ItemStack.java
+index c4d034c6a6ff176bc954c00c328512bdf67455a6..7b2010ec4955fb5788c60178c6e306ea3098e9ba 100644
+--- a/src/main/java/net/minecraft/server/ItemStack.java
++++ b/src/main/java/net/minecraft/server/ItemStack.java
+@@ -552,6 +552,7 @@ public final class ItemStack {
+         this.getItem().b(this, world, entityhuman);
+     }
+ 
++    public int getItemUseMaxDuration() { return k(); } // Paper - OBFHELPER
+     public int k() {
+         return this.getItem().e_(this);
+     }
+diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+index 9e0db30c5f99164412e97a1cdd865ca254861a78..c6173133cc458fe5a5fe6f431ab79a9abb15101e 100644
+--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
++++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+@@ -174,6 +174,13 @@ public final class CraftItemStack extends ItemStack {
+         return (handle == null) ? Material.AIR.getMaxStackSize() : handle.getItem().getMaxStackSize();
+     }
+ 
++    // Paper start
++    @Override
++    public int getMaxItemUseDuration() {
++        return handle == null ? 0 : handle.getItemUseMaxDuration();
++    }
++    // Paper end
++
+     @Override
+     public void addUnsafeEnchantment(Enchantment ench, int level) {
+         Validate.notNull(ench, "Cannot add null enchantment");