### 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
ERR_FAIL_INDEX_V(p_column, cells.size(), "");
	return cells[p_column].suffix;
}
void TreeItem::set_icon(int p_column, const Ref<Texture2D> &p_icon) {
	ERR_FAIL_INDEX(p_column, cells.size());
	if (cells[p_column].icon == p_icon) {
		return;
	}
	cells.write[p_column].icon = p_icon;
	cells.write[p_column].cached_minimum_size_dirty = true;
	_changed_notify(p_column);
}
Ref<Texture2D> TreeItem::get_icon(int p_column) const {
	ERR_FAIL_INDEX_V(p_column, cells.size(), Ref<Texture2D>());
	return cells[p_column].icon;
}
void TreeItem::set_icon_region(int p_column, const Rect2 &p_icon_region) {
	ERR_FAIL_INDEX(p_column, cells.size());
	if (cells[p_column].icon_region == p_icon_region) {
		return;
	}
	cells.write[p_column].icon_region = p_icon_region;
	cells.write[p_column].cached_minimum_size_dirty = true;
	_changed_notify(p_column);
}
Rect2 TreeItem::get_icon_region(int p_column) const {