[sddm-theme/lock screen] Tighten clock and username shadows
This patch tightens the shadows around the clock in the Breeze SDDM theme and lock screen so as to prevent the appearance of a diffuse dark glare that appears around the clock on top of very bright backgrounds.
In addition, it tightens the username/prompt shadows to match the shadows used in desktopcontainment.
Username shadows, before:
(the new shadows take after the ones in desktopcontainment)
Before (white background):
After (white background):
Reviewers: VDG, ngraham, filipf, mart
Reviewed By: VDG, ngraham, filipf, mart
Subscribers: mart, plasma-devel
Maniphest Tasks: T10325
Differential Revision: https://phabricator.kde.org/D19325