[Applets/Task Manager] Fix and improve behavior tab layouts
Summary:
Fix the group layout.
Change rest of behavior tab layout.
Rename various labels and texts.
BUG: 415649
FIXED-IN: 5.19.0
Test Plan:
Before:
The indentation of option "Group only when the Task Manager is full"
is misleading.
Reviewers: VDG, Plasma, hein, ngraham
Reviewed By: VDG, ngraham
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D26660