gdbus: fix not handling bus disconnects

gdbus: fix not handling bus disconnects

We where not dispatching data when a bus disconnects which cause
Disconnected signal to not be processed and thus causing the process to
either not exit or to not trigger callbacks registered with
g_dbus_set_disconnect_function.

To fix this now we always schedule a dispatch which will make sure data
still not processed will make its way to the proper handlers even if
disconnected.