Serious side effect of #6299 (silencing salut so gabble can connect)

[Morgan Collett]

Morgan Collett wrote:
> Many activities are calling PS get_preferred_connection() to interact
> directly with the appropriate Telepathy Connection Manager, which was
> required in the past before we expanded Presence Service's management of
> setting up channels for activities.
> 
> However, during the period when we stop salut to let gabble try to
> connect, this call fails as there is no running plugin in PS. If an
> activity is launched during this time (and there's no particular UI to
> show this other than no buddies in mesh view) and it makes this call in
> __init__ as most of them do, then it will crash with a gray screen.
> 
> This affects: Calculate, Chat, Pippy, Record, Web and Write (of the
> activities we bundle) and potentially other non-bundled activities.

I should have mentioned that there is an open bug for this: #4494, but
it's for Future Release since until now this was only triggered by salut
crashing, leaving no CMs running.