[Task Manager] Do not crop album art in tooltip

Summary:

• The standard aspect ratio of albumImage is always 1:1. We should not crop the important part of albumArt in some cases.
• Hide the window title text of media players to avoid displaying the title/artist repeatedly.

BUG: 401234
FIXED-IN: 5.16.0

Test Plan:
Before vs After:

• Breeze Dark

• Breeze Light

Reviewers: hein, broulik, ngraham, VDG, filipf, rooty

Reviewed By: ngraham, VDG, filipf, rooty

Subscribers: mvourlakos, rooty, filipf, ndavis, abetts, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D17073