### 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)
bool is_not_in_scene_or_editor = !(is_inside_tree() && Engine::get_singleton()->is_editor_hint());
	bool is_any_smoothing_valid = position_smoothing_speed > 0 || rotation_smoothing_speed > 0;
	bool enable = is_any_smoothing_valid && is_not_in_scene_or_editor;
	set_process_internal(enable);
}
void Camera2D::make_current() {
	ERR_FAIL_COND(!enabled || !is_inside_tree());
	get_tree()->call_group(group_name, "_make_current", this);
	_update_scroll();
}
void Camera2D::clear_current() {
	ERR_FAIL_COND(!is_current());
	if (viewport && !(custom_viewport && !ObjectDB::get_instance(custom_viewport_id))) {
		viewport->assign_next_enabled_camera_2d(group_name);
	}
}
bool Camera2D::is_current() const {
	if (viewport && !(custom_viewport && !ObjectDB::get_instance(custom_viewport_id))) {
		return viewport->get_camera_2d() == this;
	}
	return false;
}
void Camera2D::set_limit(Side p_side, int p_limit) {