Remove current item highlighting in the Places Panel

Remove current item highlighting in the Places Panel

In the Places Panel, there is always exactly one selected item, which is
equal to the current item. Since the selected item is highlighted by
drawing its background in a different color, it is not really necessary
to highlight additionally that it is the current item.

This is achieved by removing the calls to
KItemListWidget::setCurrent(true) from KItemListView. The "current"
information in the widget is only used for deciding if the "current item
highlighting", like an underline in Oxygen, should be drawn.

The motivation for this change is that I have seem some complaints about
the "current item" highlighting, which can be even more distracting with
non-Oxygen styles.

REVIEW: 119019