### 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_RESIZE_DISABLED,
		SUB_WINDOW_RESIZE_TOP_LEFT,
		SUB_WINDOW_RESIZE_TOP,
		SUB_WINDOW_RESIZE_TOP_RIGHT,
		SUB_WINDOW_RESIZE_LEFT,
		SUB_WINDOW_RESIZE_RIGHT,
		SUB_WINDOW_RESIZE_BOTTOM_LEFT,
		SUB_WINDOW_RESIZE_BOTTOM,
		SUB_WINDOW_RESIZE_BOTTOM_RIGHT,
		SUB_WINDOW_RESIZE_MAX
	};
	struct SubWindow {
		Window *window = nullptr;
		RID canvas_item;
		Rect2i parent_safe_rect;
	};
	
	VRSMode vrs_mode = VRS_DISABLED;
	Ref<Texture2D> vrs_texture;
	struct GUI {
		bool forced_mouse_focus = false; 
		bool mouse_in_viewport = true;
		bool key_event_accepted = false;
		HashMap<int, ObjectID> touch_focus;
		Control *mouse_focus = nullptr;
		Control *last_mouse_focus = nullptr;
		Control *mouse_click_grabber = nullptr;
		BitField<MouseButtonMask> mouse_focus_mask;