swarm: retrieve old swarm for one to one when possible

With this patch, contact left is removed in one to one. So, if
a contact left, they still receive message notification and they
will generate conversation requests and retrieve the old history.
Moreover, if they remove and re-add a contact, they will receives
a confirmation for the previous conversation and retrieve the old
history.
This avoid duplicates and read-only conversation.

GitLab: https://git.jami.net/savoirfairelinux/ring-project/-/issues/1282
Change-Id: Id820482e82e23334632e76bf4920255efb45f4cb