### 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.
_sub_window_grab_focus(nullptr);
		}
	}
	if (gui.subwindow_focused) {
		Ref<InputEventMouseMotion> mm = p_event;
		if (mm.is_valid()) {
			SubWindowResize resize = _sub_window_get_resize_margin(gui.subwindow_focused, mm->get_position());
			if (resize != SUB_WINDOW_RESIZE_DISABLED) {
				DisplayServer::CursorShape shapes[SUB_WINDOW_RESIZE_MAX] = {
					DisplayServer::CURSOR_ARROW,
					DisplayServer::CURSOR_FDIAGSIZE,
					DisplayServer::CURSOR_VSIZE,
					DisplayServer::CURSOR_BDIAGSIZE,
					DisplayServer::CURSOR_HSIZE,
					DisplayServer::CURSOR_HSIZE,
					DisplayServer::CURSOR_BDIAGSIZE,
					DisplayServer::CURSOR_VSIZE,
					DisplayServer::CURSOR_FDIAGSIZE
				};
				if (DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_CURSOR_SHAPE)) {
					DisplayServer::get_singleton()->cursor_set_shape(shapes[resize]);
				}
				return true; 
			}
		}
	}
	if (gui.subwindow_drag != SUB_WINDOW_DRAG_DISABLED) {
		return true; 
	}
	if (!gui.subwindow_focused) {