message: [kafka] improve verbosity while rebalancing consumers
diff: @@ -786,8 +786,8 @@ class KafkaRebalanceCb : public RdKafka::RebalanceCb {
  LOG(INFO) << "REBALANCE: " << partitions[partition]->topic() << "["
  << partitions[partition]->partition() << "], "
  - << partitions[partition]->offset() << " "
  - << partitions[partition]->err();
  + << "OFFSET: " << partitions[partition]->offset() << " "
  + << "ERROR_CODE: " << partitions[partition]->err();
  }
  if (err == RdKafka::ERR__ASSIGN_PARTITIONS) {
  // librdkafka does not actually look up the stored offsets before
  