Align property labels in the INDI dialog vertically on top

Summary:
If property labels are aligned vertically central, it is sometimes difficult
to identify which label belongs to which property element. Therefore the
labels are aligned vertically on top.

Reviewers: mutlaqja

Reviewed By: mutlaqja

Subscribers: kde-edu, mutlaqja

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D26641