### 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());
	cells.write[p_column].selectable = p_selectable;
}
bool TreeItem::is_selectable(int p_column) const {
	ERR_FAIL_INDEX_V(p_column, cells.size(), false);
	return cells[p_column].selectable;
}
bool TreeItem::is_selected(int p_column) {
	ERR_FAIL_INDEX_V(p_column, cells.size(), false);
	return cells[p_column].selectable && cells[p_column].selected;
}
void TreeItem::set_as_cursor(int p_column) {
	ERR_FAIL_INDEX(p_column, cells.size());
	if (!tree) {
		return;
	}
	if (tree->select_mode != Tree::SELECT_MULTI) {
		return;
	}
	if (tree->selected_item == this && tree->selected_col == p_column) {
		return;
	}
	tree->selected_item = this;
	tree->selected_col = p_column;
	tree->queue_redraw();
}
void TreeItem::select(int p_column) {