### 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)

_THREAD_SAFE_METHOD_
	EnumPosData data = { 0, 0, Point2() };
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcOrigin, (LPARAM)&data);
	return data.pos;
}
Point2i DisplayServerWindows::screen_get_position(int p_screen) const {
	_THREAD_SAFE_METHOD_
	p_screen = _get_screen_index(p_screen);
	EnumPosData data = { 0, p_screen, Point2() };
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcPos, (LPARAM)&data);
	return data.pos - _get_screens_origin();
}
typedef struct {
	int count;
	int screen;
	Size2 size;
} EnumSizeData;
typedef struct {
	int count;
	int screen;
	Rect2i rect;
} EnumRectData;
typedef struct {
	int count;
	int screen;
	float rate;
} EnumRefreshRateData;
static BOOL CALLBACK _MonitorEnumProcSize(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {