### 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)

FillRect(hdc, &rect, window_bkg_brush);
			}
			return 1;
		} break;
		case WM_PAINT: {
			Main::force_redraw();
		} break;
		case WM_SETTINGCHANGE: {
			if (lParam && CompareStringOrdinal(reinterpret_cast<LPCWCH>(lParam), -1, L"ImmersiveColorSet", -1, true) == CSTR_EQUAL) {
				if (is_dark_mode_supported() && dark_title_available) {
					BOOL value = is_dark_mode();
					::DwmSetWindowAttribute(windows[window_id].hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE, &value, sizeof(value));
				}
			}
		} break;
		case WM_THEMECHANGED: {
			if (is_dark_mode_supported() && dark_title_available) {
				BOOL value = is_dark_mode();
				::DwmSetWindowAttribute(windows[window_id].hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE, &value, sizeof(value));
			}
		} break;
		case WM_SYSCOMMAND: 
		{
			switch (wParam) 
			{
				case SC_SCREENSAVE: 
				case SC_MONITORPOWER: 
					return 0; 
				case SC_KEYMENU:
					if ((lParam >> 16) <= 0) {