### Godot version

v4.1.1.stable.official [bd6af8e0e]

### System information

Godot v4.1.1.stable - Debian GNU/Linux trixie/sid trixie - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (nvidia) - Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz (6 Threads)

### Issue description

`Area2D`s which extend beyond the bounds of the root viewport, eg. when using a `canvas_items` stretch mode, receive mouse input events even in the black bands letterboxing the game:

https://github.com/godotengine/godot/assets/441188/3beb962f-c1fa-4098-a375-f3d862013577


### Steps to reproduce

1. Set project stretch mode to either `canvas_items` or `viewport`
2. Have an `Area2D` whose `CollisionShape` extends beyond the bounds of the rendered region
3. Connect the `Area2D`'s `mouse_[entered|exited]` signal to something
4. Wave the mouse around in the black areas outside the rendered game

### Minimal reproduction project

Project used for video demo above:

[area2d-oob.zip](https://github.com/godotengine/godot/files/12207031/area2d-oob.zip)

This only demos `mouse_[entered|exited]`, but I first encountered this with the `Area2D.input_event` signal, where it received mouse clicks as well.
ERR_MAIN_THREAD_GUARD;
	emit_signal(SNAME("about_to_popup"));
	if (!get_embedder() && get_flag(FLAG_POPUP)) {
		
		SceneTree *scene_tree = get_tree();
		if (scene_tree) {
			scene_tree->notify_group_flags(SceneTree::GROUP_CALL_DEFERRED, "_viewports", NOTIFICATION_WM_WINDOW_FOCUS_OUT);
		}
	}
	
	_update_window_size();
	if (p_screen_rect != Rect2i()) {
		set_position(p_screen_rect.position);
		set_size(p_screen_rect.size);
	}
	Rect2i adjust = _popup_adjust_rect();
	if (adjust != Rect2i()) {
		set_position(adjust.position);
		set_size(adjust.size);
	}