### Godot version

v4.0.beta.custom_build [0a9e6e478]

### System information

Ubuntu, Nvidia, Vulkan

### Issue description

When a Camera2D is freed - either explicitly or by being a child of a scene that is being switched away from via a method like `get_tree().change_scene_to_file()` - then this camera somehow stays active instead of Godot properly switching to no-camera-mode.

`get_viewport().get_camera_2d()` then returns all sorts of funny things from `<Freed Object>`  (it's supposed to return `null`) to arbitrary nodes of the current scene (not cameras).

This can lead to crashes.

### Steps to reproduce

checkout the MRP.

note that the "Go to scene 2" button switches places after pressing it.
that is because a camera is still active that does not exist in the current tree.

restart it a couple of times and spam the "Go to scene 2" button.
notice the garbage output.

### Minimal reproduction project

[godot_4_camera_bug.zip](https://github.com/godotengine/godot/files/10560455/godot_4_camera_bug.zip)
CanvasItem *ci = p_control;
	while (ci) {
		Control *control = Object::cast_to<Control>(ci);
		if (control) {
			if (control->data.mouse_filter != Control::MOUSE_FILTER_IGNORE) {
				control->notification(p_what);
			}
			if (!control->is_inside_tree()) {
				break;
			}
			if (!control->is_inside_tree() || control->is_set_as_top_level()) {
				break;
			}
			if (control->data.mouse_filter == Control::MOUSE_FILTER_STOP) {
				break;
			}
		}
		if (ci->is_set_as_top_level()) {
			break;
		}
		ci = ci->get_parent_item();
	}
}
Control *Viewport::gui_find_control(const Point2 &p_global) {