### 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)

reinterpret_cast<void *>(&wd));
		if (!wd.hWnd) {
			MessageBoxW(nullptr, L"Window Creation Error.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
			windows.erase(id);
			ERR_FAIL_V_MSG(INVALID_WINDOW_ID, "Failed to create Windows OS window.");
		}
		if (p_mode == WINDOW_MODE_FULLSCREEN || p_mode == WINDOW_MODE_EXCLUSIVE_FULLSCREEN) {
			wd.fullscreen = true;
			if (p_mode == WINDOW_MODE_FULLSCREEN) {
				wd.multiwindow_fs = true;
			}
		}
		if (p_mode != WINDOW_MODE_FULLSCREEN && p_mode != WINDOW_MODE_EXCLUSIVE_FULLSCREEN) {
			wd.pre_fs_valid = true;
		}
		if (is_dark_mode_supported() && dark_title_available) {
			BOOL value = is_dark_mode();
			::DwmSetWindowAttribute(wd.hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE, &value, sizeof(value));
		}
#ifdef VULKAN_ENABLED
		if (context_vulkan) {
			if (context_vulkan->window_create(id, p_vsync_mode, wd.hWnd, hInstance, WindowRect.right - WindowRect.left, WindowRect.bottom - WindowRect.top) != OK) {
				memdelete(context_vulkan);
				context_vulkan = nullptr;
				windows.erase(id);
				ERR_FAIL_V_MSG(INVALID_WINDOW_ID, "Failed to create Vulkan Window.");
			}
			wd.context_created = true;
		}
#endif