### 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
draw_item_rect(p_item->cells.write[i], item_rect, cell_color, icon_col, outline_size, font_outline_color);
						break;
					}
					Ref<Texture2D> downarrow = theme_cache.select_arrow;
					Rect2i ir = item_rect;
					Point2i arrow_pos = item_rect.position;
					arrow_pos.x += item_rect.size.x - downarrow->get_width();
					arrow_pos.y += Math::floor(((item_rect.size.y - downarrow->get_height())) / 2.0);
					ir.size.width -= downarrow->get_width();
					if (p_item->cells[i].custom_button) {
						if (cache.hover_item == p_item && cache.hover_cell == i) {
							if (Input::get_singleton()->is_mouse_button_pressed(MouseButton::LEFT)) {
								draw_style_box(theme_cache.custom_button_pressed, ir);
							} else {
								draw_style_box(theme_cache.custom_button_hover, ir);
								cell_color = theme_cache.custom_button_font_highlight;
							}
						} else {
							draw_style_box(theme_cache.custom_button, ir);
						}
						ir.size -= theme_cache.custom_button->get_minimum_size();
						ir.position += theme_cache.custom_button->get_offset();
					}
					draw_item_rect(p_item->cells.write[i], ir, cell_color, icon_col, outline_size, font_outline_color);
					downarrow->draw(ci, arrow_pos);
				} break;
			}
			for (int j = p_item->cells[i].buttons.size() - 1; j >= 0; j--) {
				Ref<Texture2D> button_texture = p_item->cells[i].buttons[j].texture;
				Size2 button_size = button_texture->get_size() + theme_cache.button_pressed->get_minimum_size();