### 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 (user32_lib) {
		win8p_GetPointerType = (GetPointerTypePtr)GetProcAddress(user32_lib, "GetPointerType");
		win8p_GetPointerPenInfo = (GetPointerPenInfoPtr)GetProcAddress(user32_lib, "GetPointerPenInfo");
		win81p_LogicalToPhysicalPointForPerMonitorDPI = (LogicalToPhysicalPointForPerMonitorDPIPtr)GetProcAddress(user32_lib, "LogicalToPhysicalPointForPerMonitorDPI");
		winink_available = win8p_GetPointerType && win8p_GetPointerPenInfo;
	}
	if (winink_available) {
		tablet_drivers.push_back("winink");
	}
	if (OS::get_singleton()->is_hidpi_allowed()) {
		HMODULE Shcore = LoadLibraryW(L"Shcore.dll");
		if (Shcore != nullptr) {
			typedef HRESULT(WINAPI * SetProcessDpiAwareness_t)(SHC_PROCESS_DPI_AWARENESS);
			SetProcessDpiAwareness_t SetProcessDpiAwareness = (SetProcessDpiAwareness_t)GetProcAddress(Shcore, "SetProcessDpiAwareness");
			if (SetProcessDpiAwareness) {
				SetProcessDpiAwareness(SHC_PROCESS_SYSTEM_DPI_AWARE);
			}
		}
	}
	memset(&wc, 0, sizeof(WNDCLASSEXW));
	wc.cbSize = sizeof(WNDCLASSEXW);
	wc.style = CS_OWNDC | CS_DBLCLKS;
	wc.lpfnWndProc = (WNDPROC)::WndProc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hInstance = hInstance ? hInstance : GetModuleHandle(nullptr);
	wc.hIcon = LoadIcon(nullptr, IDI_WINLOGO);
	wc.hCursor = nullptr;
	wc.hbrBackground = nullptr;
	wc.lpszMenuName = nullptr;