### 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.
for (int i = 0; i < gui.sub_windows.size(); i++) {
		if (gui.sub_windows[i].window == p_window) {
			return i;
		}
	}
	return -1;
}
void Viewport::_update_viewport_path() {
	if (viewport_textures.is_empty()) {
		return;
	}
	Node *scene_root = get_scene_file_path().is_empty() ? get_owner() : this;
	if (!scene_root && is_inside_tree()) {
		scene_root = get_tree()->get_edited_scene_root();
	}
	if (scene_root && (scene_root == this || scene_root->is_ancestor_of(this))) {
		NodePath path_in_scene = scene_root->get_path_to(this);
		for (ViewportTexture *E : viewport_textures) {
			E->path = path_in_scene;
		}
	}
}
void Viewport::_notification(int p_what) {