default to no arrows
Summary:
as the last part of the new design, try to not have arrows
in the scrollbars by default (just change of default,
all the functionality is there)
Test Plan: default is correctly picked up
Reviewers: Plasma, VDG, hpereiradacosta
Reviewed By: hpereiradacosta
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D3378