[logout-greeter] Set window class name

This matches what kwin's effects have always been searching for. It only
used to appear to work as "ksmserver ksmserver" was checked in previous
versions.

BUG: 444898
BUG: 444899

logout-greeter/shutdowndlg.cpp

@@ -79,8 +79,8 @@ KSMShutdownDlg::KSMShutdownDlg(QWindow *parent, KWorkSpace::ShutdownType sdtype)
                         strlen("logoutdialog"));
 
         XClassHint classHint;
-        classHint.res_name = const_cast<char *>("ksmserver");
-        classHint.res_class = const_cast<char *>("ksmserver");
+        classHint.res_name = const_cast<char *>("ksmserver-logout-greeter");
+        classHint.res_class = const_cast<char *>("ksmserver-logout-greeter");
         XSetClassHint(QX11Info::display(), winId(), &classHint);
     }