Boost theme removes the last item action.
This adds an extra node so the profile run details page breadcrumb is clickable in both Classic and Boost themes.
dirname() is a slow function compared with __DIR__ and using
'/../'. Moodle has a large number of legacy files that are included
each time a page loads and is not able to use an autoloader as it is
functional code. This allows those required includes to perform as
best as possible in this situation.