Rollback of compressed messages return too many credits

[AntonRoskvist]

When messages are compressed and get small enough to pass as regular messages, consumer credits can get thrown off balance, in particular following a rollback.

This has two effects:

1. Consumers can get more messages "delivering" than what consumerWindowSize should allow.
2. Over time, accumulated credits can overflow, causing negative credits and thereby marking the consumer as "busy".

I am open to rewriting the test to be faster if you have any recommendations on it, I had some trouble formulating it in a good way that would demonstrate the issue.