### 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_FAIL_COND(!is_inside_tree());
	for (int i = 0; i < gui.sub_windows.size(); i++) {
		ERR_FAIL_COND(gui.sub_windows[i].window == p_window);
	}
	if (gui.sub_windows.size() == 0) {
		subwindow_canvas = RS::get_singleton()->canvas_create();
		RS::get_singleton()->viewport_attach_canvas(viewport, subwindow_canvas);
		RS::get_singleton()->viewport_set_canvas_stacking(viewport, subwindow_canvas, SUBWINDOW_CANVAS_LAYER, 0);
	}
	SubWindow sw;
	sw.canvas_item = RS::get_singleton()->canvas_item_create();
	RS::get_singleton()->canvas_item_set_parent(sw.canvas_item, subwindow_canvas);
	sw.window = p_window;
	gui.sub_windows.push_back(sw);
	if (gui.subwindow_drag == SUB_WINDOW_DRAG_DISABLED) {
		if (p_window->get_flag(Window::FLAG_NO_FOCUS)) {
			_sub_window_update_order();
		} else {
			_sub_window_grab_focus(p_window);
		}
	} else {
		int index = _sub_window_find(gui.currently_dragged_subwindow);
		sw = gui.sub_windows[index];
		gui.sub_windows.remove_at(index);
		gui.sub_windows.push_back(sw);
		_sub_window_update_order();
	}
	RenderingServer::get_singleton()->viewport_set_parent_viewport(p_window->viewport, viewport);
}
void Viewport::_sub_window_update(Window *p_window) {