### 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(p_column, cells.size());
	if (cells[p_column].mode == p_mode) {
		return;
	}
	Cell &c = cells.write[p_column];
	c.mode = p_mode;
	c.min = 0;
	c.max = 100;
	c.step = 1;
	c.val = 0;
	c.checked = false;
	c.icon = Ref<Texture2D>();
	c.text = "";
	c.dirty = true;
	c.icon_max_w = 0;
	c.cached_minimum_size_dirty = true;
	_changed_notify(p_column);
}
TreeItem::TreeCellMode TreeItem::get_cell_mode(int p_column) const {
	ERR_FAIL_INDEX_V(p_column, cells.size(), TreeItem::CELL_MODE_STRING);
	return cells[p_column].mode;
}
void TreeItem::set_edit_multiline(int p_column, bool p_multiline) {