### 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)

if (result == Success && data) {
		Atom *atoms = (Atom *)data;
		Atom wm_act_max_horz;
		Atom wm_act_max_vert;
		if (strcmp(p_atom_name, "_NET_WM_STATE") == 0) {
			wm_act_max_horz = XInternAtom(x11_display, "_NET_WM_STATE_MAXIMIZED_HORZ", False);
			wm_act_max_vert = XInternAtom(x11_display, "_NET_WM_STATE_MAXIMIZED_VERT", False);
		} else {
			wm_act_max_horz = XInternAtom(x11_display, "_NET_WM_ACTION_MAXIMIZE_HORZ", False);
			wm_act_max_vert = XInternAtom(x11_display, "_NET_WM_ACTION_MAXIMIZE_VERT", False);
		}
		bool found_wm_act_max_horz = false;
		bool found_wm_act_max_vert = false;
		for (uint64_t i = 0; i < len; i++) {
			if (atoms[i] == wm_act_max_horz) {
				found_wm_act_max_horz = true;
			}
			if (atoms[i] == wm_act_max_vert) {
				found_wm_act_max_vert = true;
			}
			if (found_wm_act_max_horz || found_wm_act_max_vert) {
				retval = true;
				break;
			}
		}
		XFree(data);
	}
	return retval;
}
bool DisplayServerX11::_window_minimize_check(WindowID p_window) const {