Revert "KAFKA-12468, KAFKA-13659, KAFKA-12566: Fix MM2 causing negati…

[jjaakola-aiven]

…ve downstream lag, syncing stale offsets, and flaky integration tests (#13178)"

This reverts commit ead8dfb9fae684a8ca9a8078a0d83c09951da85e.

The fix for KAFKA-12468 introduced an issue with consumer group offset syncing. See:

• https://issues.apache.org/jira/browse/KAFKA-14797 -> https://github.com/apache/kafka/pull/13367
• https://issues.apache.org/jira/browse/KAFKA-14666