Restore new tab behavior
Summary:
As part of the QTabBar refactoring, honouring of the new tab behaviour
setting was lost. Restore using a simpler implementation that simply
asks QTabWidget for the current index.
BUG: 396701
Reviewers: Konsole, hindenburg, tcanabrava
Subscribers: konsole-devel
Tags: Konsole
Differential Revision: https://phabricator.kde.org/D15828