This is action item #2 from https://phabricator.kde.org/T9444#160267. The `system-switch-user` Breeze Plasma theme icon does not match the visual style of all the other power-related icons in system.svgz. The other ones are symmetrical and generally round in appearance. `system-switch-user` is neither. It should be more like https://www.flaticon.com/free-icon/switch-arrow-button_19879#term=switch&page=2&position=69
Alternatively, we could do something with back-and-forth arrows between user silhouettes, or something like that. But basically the current "arrow pointing at a head" iconography maybe isn't the best we can do here.
Resolved as part of https://phabricator.kde.org/D19020