Mqtt session takeover is not working when the second client connects to the same Zilla instance

[bmaidics]

We're not receiving the reset frame on the group stream -> not leaving the group with the first connection
repro:
start 1 zilla
connect using mosquitto_sub -V '5' -t 'newTopic5' -d -i 'my-client' -p 1883
connect again from a different terminal: mosquitto_sub -V '5' -t 'newTopic5' -d -i 'my-client' -p 1883
First connection should be teared down

Since we connect to the same zilla instance with the same consumer group instanceId, when we connect with the second client the group stream assigns the previous memberId to the JoinGroupRequest (not empty as I think it should be). Kafka realizes, that it's already a member, and that's it. It's already the leader -> we're not leaving the group with the first one.

Added the two pcaps for the first and the second connections.
join_requests.zip