destroy the video_output widget when the call is disconnected
destroy the video_output widget when the call is disconnected

There is no point to destroy it when redialing to recreate it immediately
after.

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