### 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
item_rect.position.x = get_size().width - item_rect.position.x - item_rect.size.x;
			}
			Point2i text_pos = item_rect.position;
			text_pos.y += Math::floor(p_draw_ofs.y) - _get_title_button_height();
			int text_width = p_item->cells[i].text_buf->get_size().x;
			switch (p_item->cells[i].mode) {
				case TreeItem::CELL_MODE_STRING: {
					draw_item_rect(p_item->cells.write[i], item_rect, cell_color, icon_col, outline_size, font_outline_color);
				} break;
				case TreeItem::CELL_MODE_CHECK: {
					Ref<Texture2D> checked = theme_cache.checked;
					Ref<Texture2D> unchecked = theme_cache.unchecked;
					Ref<Texture2D> indeterminate = theme_cache.indeterminate;
					Point2i check_ofs = item_rect.position;
					check_ofs.y += Math::floor((real_t)(item_rect.size.y - checked->get_height()) / 2);
					if (p_item->cells[i].indeterminate) {
						indeterminate->draw(ci, check_ofs);
					} else if (p_item->cells[i].checked) {
						checked->draw(ci, check_ofs);
					} else {
						unchecked->draw(ci, check_ofs);
					}
					int check_w = checked->get_width() + theme_cache.h_separation;
					text_pos.x += check_w;
					item_rect.size.x -= check_w;
					item_rect.position.x += check_w;
					draw_item_rect(p_item->cells.write[i], item_rect, cell_color, icon_col, outline_size, font_outline_color);
				} break;
				case TreeItem::CELL_MODE_RANGE: {
					if (!p_item->cells[i].text.is_empty()) {