### Godot version

Godot Engine v4.0.stable.official.92bee43ad

### System information

Windows 10

### Issue description

The documentation states that passing ```null``` into the image parameter of ```set_custom_mouse_cursor``` will change it back to the system cursor, however I find that it removes the cursor's image entirely, rather than setting it to the system's cursor.


### Steps to reproduce

```var isimage = false
var theimage = load("res://final.png")

func _on_my_button_pressed():
    if isimage == false:
        Input.set_custom_mouse_cursor(theimage, Input.CURSOR_ARROW, Vector2(16,16))
        isimage = true
        
    else:
        Input.set_custom_mouse_cursor(null)
        isimage = false```

When the button is pressed, the cursor is meant to change to the new cursor. When it has been pressed a second time, it changes back to the default cursor. However, upon pressing it a second time, it simply disappears. The cursor becomes visible again when the cursor exits and re-enters the window.

### Minimal reproduction project

[null mouse.zip](https://github.com/godotengine/godot/files/10901969/null.mouse.zip)

encode_uint32(40, &icon_bmp[0]);
	encode_uint32(w, &icon_bmp[4]);
	encode_uint32(h * 2, &icon_bmp[8]);
	encode_uint16(1, &icon_bmp[12]);
	encode_uint16(32, &icon_bmp[14]);
	encode_uint32(BI_RGB, &icon_bmp[16]);
	encode_uint32(w * h * 4, &icon_bmp[20]);
	encode_uint32(0, &icon_bmp[24]);
	encode_uint32(0, &icon_bmp[28]);
	encode_uint32(0, &icon_bmp[32]);
	encode_uint32(0, &icon_bmp[36]);
	uint8_t *wr = &icon_bmp[40];
	const uint8_t *r = icon->get_data().ptr();
	for (int i = 0; i < h; i++) {
		for (int j = 0; j < w; j++) {
			const uint8_t *rpx = &r[((h - i - 1) * w + j) * 4];
			uint8_t *wpx = &wr[(i * w + j) * 4];
			wpx[0] = rpx[2];
			wpx[1] = rpx[1];
			wpx[2] = rpx[0];
			wpx[3] = rpx[3];
		}
	}
	HICON hicon = CreateIconFromResource(icon_bmp, icon_len, TRUE, 0x00030000);
	
	SendMessage(windows[MAIN_WINDOW_ID].hWnd, WM_SETICON, ICON_SMALL, (LPARAM)hicon);
	
	SendMessage(windows[MAIN_WINDOW_ID].hWnd, WM_SETICON, ICON_BIG, (LPARAM)hicon);
}
void DisplayServerWindows::window_set_vsync_mode(DisplayServer::VSyncMode p_vsync_mode, WindowID p_window) {