### 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;
	gui.canvas_sort_index = 0;
}
int Viewport::gui_get_canvas_sort_index() {
	ERR_MAIN_THREAD_GUARD_V(0);
	return gui.canvas_sort_index++;
}
void Viewport::gui_release_focus() {
	ERR_MAIN_THREAD_GUARD;
	if (gui.key_focus) {
		Control *f = gui.key_focus;
		gui.key_focus = nullptr;
		f->notification(Control::NOTIFICATION_FOCUS_EXIT, true);
		f->queue_redraw();
	}
}
Control *Viewport::gui_get_focus_owner() const {
	ERR_READ_THREAD_GUARD_V(nullptr);
	return gui.key_focus;
}
void Viewport::set_msaa_2d(MSAA p_msaa) {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_INDEX(p_msaa, MSAA_MAX);
	if (msaa_2d == p_msaa) {
		return;
	}
	msaa_2d = p_msaa;
	RS::get_singleton()->viewport_set_msaa_2d(viewport, RS::ViewportMSAA(p_msaa));
}
Viewport::MSAA Viewport::get_msaa_2d() const {