`http-kafka` will `fetch` messages that have been deleted by a retention policy

[vordimous]

Describe the bug
Zilla is returning messages in a GET request using http-kafka binding fetch that have been deleted from the topic via a retention policy.

To Reproduce
Steps to reproduce the behavior:

1. use any http-kafka fetch config (bug was confirmed using the quickstart and taxi-demo)
2. configure the topic with --config cleanup.policy=compact,delete --config delete.retention.ms=6000 --config retention.ms=6000
3. produce messages to the topic
4. wait for messages to be deleted
5. See all messages in the GET response, but response should not have deleted messages
6. restart Zilla
7. GET response now shows the correct data

Expected behavior
Zilla doesn't return delete messages.