In `WPPlaylistView::ended()`, at the end of a playlist, set the index to `0` and call `->setCurrent()` instead of `->loadCurrent()` so that the first track is properly highlighted.

Fixes #28428.


git-svn-id: https://develop.svn.wordpress.org/trunk@28649 602fd350-edb4-49c9-b593-d223f7449a82