Add removePlayerInitialization func

src/main/java/net/minestom/server/network/ConnectionManager.java

@@ -302,6 +302,17 @@ public final class ConnectionManager {
         this.playerInitializations.add(playerInitialization);
     }
 
+    /**
+     * Removes an existing player initialization consumer.
+     * <p>
+     * Removal of player initializations should be done by reference, and not cloning.
+     *
+     * @param playerInitialization the {@link Player} initialization consumer
+     */
+    public void removePlayerInitialization(@NotNull Consumer<Player> playerInitialization) {
+        this.playerInitializations.remove(playerInitialization);
+    }
+
     /**
      * Gets the kick reason when the server is shutdown using {@link MinecraftServer#stopCleanly()}.
      *