SystemMonitor: fix dragging between panel and desktop

m_sensorFaceController needs to be told about the current applet config group every time we reload the config because is not guaranteed to stay the same during the applet lifetime For instance when the applet is dragged between the desktop and the panel

depends on libksysguard!439 (merged)

BUG: 508184
FIXED-IN: 6.5.0

(cherry picked from commit 811bca36)

e75b4eb0 SystemMonitor: fix dragging between panel and desktop 94a09327 adapt to api change

Co-authored-by: Marco Martin notmart@gmail.com