The group call update message after starting a group call is currently only
sent in the onLocalDeviceStateChanged callback. But often the peekInfo is
not available yet when the connection state changes to Joined, effectively
preventing the group call update message to be sent.
This commit also sends the message in the onPeekChanged callback. It is still
only sent at most once, which is ensured by the updateMessageState check.
See [#5001][0].
[0]: https://github.com/signalapp/Signal-Desktop/pull/5001