Consumer fetcher should handle UnsupportedVersionException more diligently

Today if the consumer is talking to an older versioned broker that does not support newer fetch versions, it will simply block without printing any warning logs. This is because when UnsupportedVersionException gets raised inside ConsumerNetworkClient, the Fetcher's handling logic is only logging it and moves on (and hence retries forever):

                       @Override
                        public void onFailure(RuntimeException e) {
                            log.debug("Fetch request {} to {} failed", request.fetchData(), fetchTarget, e);
                        }

We should at least logging UnsupportedVersionException specifically as WARN or even let the consumer to fail fast and gracefully upon this error.

Side note: There are two system tests in streams_broker_compatibility_test.ps that are disabled atm – after this got fixed, we need to re-enable those tests (and also update them accordingly).