runners/helprunner: Fix launching of plasmasearch kcm with args
Test Plan: Open Krunner and type ? Scroll though the list of results until one has a configure button Click that button and check if systemsettings opens and the runner's KCM is opened
Test Plan: Open Krunner and type ? Scroll though the list of results until one has a configure button Click that button and check if systemsettings opens and the runner's KCM is opened