### 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 use_occlusion_culling;
}
void Viewport::set_debug_draw(DebugDraw p_debug_draw) {
	debug_draw = p_debug_draw;
	RS::get_singleton()->viewport_set_debug_draw(viewport, RS::ViewportDebugDraw(p_debug_draw));
}
Viewport::DebugDraw Viewport::get_debug_draw() const {
	return debug_draw;
}
int Viewport::get_render_info(RenderInfoType p_type, RenderInfo p_info) {
	return RS::get_singleton()->viewport_get_render_info(viewport, RS::ViewportRenderInfoType(p_type), RS::ViewportRenderInfo(p_info));
}
void Viewport::set_snap_controls_to_pixels(bool p_enable) {
	snap_controls_to_pixels = p_enable;
}
bool Viewport::is_snap_controls_to_pixels_enabled() const {
	return snap_controls_to_pixels;
}
void Viewport::set_snap_2d_transforms_to_pixel(bool p_enable) {
	snap_2d_transforms_to_pixel = p_enable;
	RS::get_singleton()->viewport_set_snap_2d_transforms_to_pixel(viewport, snap_2d_transforms_to_pixel);
}
bool Viewport::is_snap_2d_transforms_to_pixel_enabled() const {
	return snap_2d_transforms_to_pixel;
}
void Viewport::set_snap_2d_vertices_to_pixel(bool p_enable) {
	snap_2d_vertices_to_pixel = p_enable;
	RS::get_singleton()->viewport_set_snap_2d_vertices_to_pixel(viewport, snap_2d_vertices_to_pixel);
}
bool Viewport::is_snap_2d_vertices_to_pixel_enabled() const {