Reduce blank space inside tooltip's header
Summary: Make the tooltip as compact as possible. This is also consistent with texts inside playerControlRow
Test Plan:
Before:
After:
Reviewers: Plasma, VDG, ndavis, ngraham
Reviewed By: VDG, ndavis, ngraham
Subscribers: ngraham, davidedmundson, ndavis, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D27262