### 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
uint64_t time = OS::get_singleton()->get_ticks_usec() / 1000; 
	uint64_t diff = time - last_keypress;
	if (diff > uint64_t(GLOBAL_GET("gui/timers/incremental_search_max_interval_msec"))) {
		incr_search = p_add;
	} else if (incr_search != p_add) {
		incr_search += p_add;
	}
	last_keypress = time;
	int col;
	TreeItem *item = search_item_text(incr_search, &col, true);
	if (!item) {
		return;
	}
	if (select_mode == SELECT_MULTI) {
		item->set_as_cursor(col);
	} else {
		item->select(col);
	}
	ensure_cursor_is_visible();
}
TreeItem *Tree::_find_item_at_pos(TreeItem *p_item, const Point2 &p_pos, int &r_column, int &h, int &section) const {