馃崚 startkde: Specify --type=method_call to correctly notify ksplash
In 3e295c33 (startkde: Avoid waiting when notifying ksplash is up, 2024-10-11) the invocation of the dbus interface was changed from qdbus to dbus-send. The former defaults to calling a method, whilst the latter defaults to sending a signal, causing the setStage method to never be called.
Instead of using the default behaviour, specify explicitly that we want to call a method using --type=method_call.