### 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)

XINPUT_CLIENT_VERSION_MAJOR, XINPUT_CLIENT_VERSION_MINOR, xi_major_query, xi_minor_query));
	}
	xi.absolute_devices.clear();
	xi.touch_devices.clear();
	xi.pen_inverted_devices.clear();
	xi.last_relative_time = 0;
	int dev_count;
	XIDeviceInfo *info = XIQueryDevice(x11_display, XIAllDevices, &dev_count);
	for (int i = 0; i < dev_count; i++) {
		XIDeviceInfo *dev = &info[i];
		if (!dev->enabled) {
			continue;
		}
		if (!(dev->use == XISlavePointer || dev->use == XIFloatingSlave)) {
			continue;
		}
		bool direct_touch = false;
		bool absolute_mode = false;
		int resolution_x = 0;
		int resolution_y = 0;
		double abs_x_min = 0;
		double abs_x_max = 0;
		double abs_y_min = 0;
		double abs_y_max = 0;
		double pressure_min = 0;
		double pressure_max = 0;
		double tilt_x_min = 0;
		double tilt_x_max = 0;
		double tilt_y_min = 0;
		double tilt_y_max = 0;