Remove unneeded options in GTK KCM
Summary:
Since font, icons, cursor theme, toolbar style, icons in menus and buttons settings are now in sync with corresponding plasma settings, they shouldn't be in GTK KCM anymore.
Depends on D24743
BUG: 406740
BUG: 401008
BUG: 401123
FIXED-IN: 5.18.0
Test Plan:
Check if nothing breaks in GTK KCM functionality, that is left.
Reviewers: VDG, Plasma, ngraham, nicolasfella
Reviewed By: VDG, ngraham, nicolasfella
Subscribers: apol, ngraham, broulik, filipf, GB_2, plasma-devel
Maniphest Tasks: T10611
Differential Revision: https://phabricator.kde.org/D24744