I don’t see an easy way to restore this toolbar. It looks like the toolbar items were deleted from the code for good.
The page you linked is about using a tree component on your own custom manager page.
In this case it is different, because the tree component is already existent and part of the default manager UI.
The only option I see to add toolbar items, would be to add some custom javascript code to the page (in a plugin). But you would need to have some knowledge of Ext.js to make it work.