### 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.
if (get_base_window() == p_window) {
		gui_release_focus();
	}
}
bool Viewport::_gui_control_has_focus(const Control *p_control) {
	return gui.key_focus == p_control;
}
void Viewport::_gui_control_grab_focus(Control *p_control) {
	if (gui.key_focus && gui.key_focus == p_control) {
		
		return;
	}
	get_tree()->call_group("_viewports", "_gui_remove_focus_for_window", (Node *)get_base_window());
	if (p_control->is_inside_tree() && p_control->get_viewport() == this) {
		gui.key_focus = p_control;
		emit_signal(SNAME("gui_focus_changed"), p_control);
		p_control->notification(Control::NOTIFICATION_FOCUS_ENTER);
		p_control->queue_redraw();
	}
}
void Viewport::_gui_accept_event() {