McdDispatcher: don't keep CTXREF15 to the dispatcher context
McdDispatcher: don't keep CTXREF15 to the dispatcher context

Now that the McdDispatchOperation is self-contained, the dispatcher
context can be freed as soon as C filters have been run.

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control