### 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
first_child = ti;
		if (!children_cache.is_empty()) {
			children_cache.insert(0, ti);
		}
	}
	ti->parent = this;
	return ti;
}
void TreeItem::add_child(TreeItem *p_item) {
	ERR_FAIL_NULL(p_item);
	ERR_FAIL_COND(p_item->tree);
	ERR_FAIL_COND(p_item->parent);
	p_item->_change_tree(tree);
	p_item->parent = this;
	TreeItem *item_prev = first_child;
	while (item_prev && item_prev->next) {
		item_prev = item_prev->next;
	}
	if (item_prev) {
		item_prev->next = p_item;
		p_item->prev = item_prev;
	} else {
		first_child = p_item;
	}
	if (!children_cache.is_empty()) {
		children_cache.append(p_item);
	}
	validate_cache();
}
void TreeItem::remove_child(TreeItem *p_item) {