Remove unnecessary override

[PotatoPresident]

Removed GenericIronChestBlockEntity#createMenu override. This is necessary as it calls createScreenHandler.

    public ScreenHandler createMenu(int i, PlayerInventory playerInventory, PlayerEntity playerEntity) {
        return this.checkUnlocked(playerEntity) ? this.createScreenHandler(i, playerInventory) : null;
    }

Fixes compat with vanilla chest lock system and mods that use it.