### 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
if (p_item->cells[i].custom_bg_color) {
				Rect2 r = cell_rect;
				if (i == 0) {
					r.position.x = p_draw_ofs.x;
					r.size.x = item_width + ofs;
				} else {
					r.position.x -= theme_cache.h_separation;
					r.size.x += theme_cache.h_separation;
				}
				if (rtl) {
					r.position.x = get_size().width - r.position.x - r.size.x;
				}
				if (p_item->cells[i].custom_bg_outline) {
					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, r.size.x, 1), p_item->cells[i].bg_color);
					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y + r.size.y - 1, r.size.x, 1), p_item->cells[i].bg_color);
					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, 1, r.size.y), p_item->cells[i].bg_color);
					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x + r.size.x - 1, r.position.y, 1, r.size.y), p_item->cells[i].bg_color);
				} else {
					RenderingServer::get_singleton()->canvas_item_add_rect(ci, r, p_item->cells[i].bg_color);
				}
			}
			if (drop_mode_flags && drop_mode_over) {
				Rect2 r = cell_rect;
				if (rtl) {
					r.position.x = get_size().width - r.position.x - r.size.x;
				}
				if (drop_mode_over == p_item) {
					if (drop_mode_section == 0 || drop_mode_section == -1) {
						
						RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, r.size.x, 1), theme_cache.drop_position_color);