VideobridgeExpireThread is created but not started

[dsmeytis]

Hello @bgrozev! I'm not really sure whether it is a typo or done on purpose but I noticed that during VideobridgeExpireThread move from Videobridge to Main in commit b623d6a call to VideobridgeExpireThread.start() was lost.
Again, maybe it is done on purpose but in my deployment it leads to a weird situation that peers who lost connection are getting stuck in "reconnecting" state without being expired.

[jitsi-jenkins]

Hi, thanks for your contribution!
If you haven't already done so, could you please make sure you sign our CLA (https://jitsi.org/icla for individuals and https://jitsi.org/ccla for corporations)? We would unfortunately be unable to merge your patch unless we have that piece :(.

[JonathanLennox]

Jenkins, test this please