Use a broom-style icon for clearing clipboard and notification history

Summary: Use Breeze's new broom-style icon for the {nav Clear History} buttons in the Klipper and Notification plasmoids.

Test Plan:
With Frameworks 5.48, the broom-style icon will be shown:
{F6100570}
{F6103810}

With an earlier Frameworks version or a different icon theme, a backspace-style icon will be displayed:
{F6100573}

Reviewers: broulik, Fuchs, #plasma, davidedmundson

Reviewed By: Fuchs, #plasma, davidedmundson

Subscribers: Zren, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D14105