### 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_
	if (!windows.has(MAIN_WINDOW_ID)) {
		return;
	}
	
	
	String text = p_text.replace("\r\n", "\n").replace("\n", "\r\n"); 
	if (!OpenClipboard(windows[MAIN_WINDOW_ID].hWnd)) {
		ERR_FAIL_MSG("Unable to open clipboard.");
	}
	EmptyClipboard();
	Char16String utf16 = text.utf16();
	HGLOBAL mem = GlobalAlloc(GMEM_MOVEABLE, (utf16.length() + 1) * sizeof(WCHAR));
	ERR_FAIL_COND_MSG(mem == nullptr, "Unable to allocate memory for clipboard contents.");
	LPWSTR lptstrCopy = (LPWSTR)GlobalLock(mem);
	memcpy(lptstrCopy, utf16.get_data(), (utf16.length() + 1) * sizeof(WCHAR));
	GlobalUnlock(mem);
	SetClipboardData(CF_UNICODETEXT, mem);
	
	CharString utf8 = text.utf8();
	mem = GlobalAlloc(GMEM_MOVEABLE, utf8.length() + 1);
	ERR_FAIL_COND_MSG(mem == nullptr, "Unable to allocate memory for clipboard contents.");
	LPTSTR ptr = (LPTSTR)GlobalLock(mem);
	memcpy(ptr, utf8.get_data(), utf8.length());
	ptr[utf8.length()] = 0;
	GlobalUnlock(mem);
	SetClipboardData(CF_TEXT, mem);
	CloseClipboard();
}
String DisplayServerWindows::clipboard_get() const {