[lxqt] switch to Matcha theme and overlay cleanup

editions/lxqt

overlays/lxqt/etc/sddm.conf

overlays/lxqt/etc/skel/.config/Kvantum/kvantum.kvconfig

overlays/lxqt/etc/skel/.config/gtk-3.0/settings.ini

overlays/lxqt/etc/skel/.config/lximage-qt/settings.conf

overlays/lxqt/etc/skel/.config/lxqt/lxqt-runner.conf

overlays/lxqt/etc/skel/.config/lxqt/notifications.conf

overlays/lxqt/etc/skel/.config/lxqt/power.conf

...qt/etc/skel/.config/manjaro/manjaro-settings-manager.conf

overlays/lxqt/etc/skel/.config/octopi/octopi.conf

overlays/lxqt/etc/skel/.config/pcmanfm-qt/lxqt/settings.conf