### Godot version

4.2 dev1

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description

Calling `Tree.propagate_check()` after an item is unchecked does not properly uncheck the parents. They are left in partially checked state.

It's easy to observe in theme editor:

https://github.com/godotengine/godot/assets/2223172/71d0479c-0a5e-48d3-957f-d90379a95c22



### Steps to reproduce

1. Edit a Theme resource
2. Go to Manage Items... menu
3. Go to Import Items tab
4. Unfold something
5. Check and uncheck a child checkbox

### Minimal reproduction project

N/A
int size = get_child_count();
	TypedArray<TreeItem> arr;
	arr.resize(size);
	for (int i = 0; i < size; i++) {
		arr[i] = children_cache[i];
	}
	return arr;
}
void TreeItem::clear_children() {
	TreeItem *c = first_child;
	while (c) {
		TreeItem *aux = c;
		c = c->get_next();
		aux->parent = nullptr; 
		memdelete(aux);
	}
	first_child = nullptr;
};
int TreeItem::get_index() {
	int idx = 0;
	TreeItem *c = this;
	while (c) {
		c = c->get_prev();
		idx++;
	}
	return idx - 1;
}
#ifdef DEV_ENABLED
void TreeItem::validate_cache() const {