Chart: Fix Bug 240520 - No axes lines when creating new chart

Summary:
Turns out KChart needs a explicitly set pen to draw ruler lines.
KChart 2.7.0 will have the option to set a pen int KChart::RulerAttributes

BUG: 240520

Subscribers: Calligra-Devel-list

Tags: #calligra:_3.0

Differential Revision: https://phabricator.kde.org/D28820