contact_manager_status_changed_cb: ignore disconnected account
contact_manager_status_changed_cb: ignore disconnected account

There is no point to start tracking an account which is about to be removed.
Furthemore, this avoid to re-add previoulsy invalidated connections (#603361).

GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets