Use vanilla's entrypoint for GameTest servers

src/main/java/net/minecraftforge/gametest/GameTestMain.java

@@ -1,16 +0,0 @@
-/*
- * Copyright (c) Forge Development LLC and contributors
- * SPDX-License-Identifier: LGPL-2.1-only
- */
-
-package net.minecraftforge.gametest;
-
-import net.minecraft.server.Main;
-
-public class GameTestMain {
-    public static void main(String[] args) {
-        System.setProperty("forge.enableGameTest", "true");
-        System.setProperty("forge.gameTestServer", "true");
-        Main.main(args);
-    }
-}