Otherwise if we show the plasma-nm applet twice, m_sensors won't be empty
and we won't be able to fect the connection speed data.
git blame points to
https://github.com/KDE/kde-workspace/commit/ba7444f99ab08cf0a305899bf66879314bd0d5a9
and
https://github.com/KDE/kde-workspace/commit/235fea1868b560acf32c5c13a3d16ef233b50be6
but they don't really explain why setData() was called only if m_sensors
was empty.
BUG: 380209