### 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 option = (int)p_item->cells[p_col].val;
			valtext = RTR("(Other)");
			Vector<String> strings = p_item->cells[p_col].text.split(",");
			for (int j = 0; j < strings.size(); j++) {
				int value = j;
				if (!strings[j].get_slicec(':', 1).is_empty()) {
					value = strings[j].get_slicec(':', 1).to_int();
				}
				if (option == value) {
					valtext = strings[j].get_slicec(':', 0);
					break;
				}
			}
		} else {
			valtext = String::num(p_item->cells[p_col].val, Math::range_step_decimals(p_item->cells[p_col].step));
		}
	} else {
		valtext = p_item->cells[p_col].text;
	}
	if (!p_item->cells[p_col].suffix.is_empty()) {
		valtext += " " + p_item->cells[p_col].suffix;
	}
	if (p_item->cells[p_col].text_direction == Control::TEXT_DIRECTION_INHERITED) {
		p_item->cells.write[p_col].text_buf->set_direction(is_layout_rtl() ? TextServer::DIRECTION_RTL : TextServer::DIRECTION_LTR);
	} else {
		p_item->cells.write[p_col].text_buf->set_direction((TextServer::Direction)p_item->cells[p_col].text_direction);
	}
	Ref<Font> font;
	if (p_item->cells[p_col].custom_font.is_valid()) {
		font = p_item->cells[p_col].custom_font;