### 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)
return vrs_mode;
}
void Viewport::set_vrs_texture(Ref<Texture2D> p_texture) {
	vrs_texture = p_texture;
	
	RID tex = p_texture.is_valid() ? p_texture->get_rid() : RID();
	RS::get_singleton()->viewport_set_vrs_texture(viewport, tex);
}
Ref<Texture2D> Viewport::get_vrs_texture() const {
	return vrs_texture;
}
DisplayServer::WindowID Viewport::get_window_id() const {
	return DisplayServer::MAIN_WINDOW_ID;
}
Viewport *Viewport::get_parent_viewport() const {
	ERR_FAIL_COND_V(!is_inside_tree(), nullptr);
	if (!get_parent()) {
		return nullptr; 
	}
	return get_parent()->get_viewport();
}
void Viewport::set_embedding_subwindows(bool p_embed) {
	gui.embed_subwindows_hint = p_embed;
}
bool Viewport::is_embedding_subwindows() const {