Fixed integration tests (#22)
### Motivation
KafkaApiTest is failing
### Modifications
1. conversion between Pulsar topic name and Kafka TopicPartition ended up with TopicPartition using name with "-partition-<partition idx>"
2. Seek was not working correctly:
PulsarKafkaConsumer seeks to beginning, as asked.
Clears lastReceivedOffset in the process.
on poll it checks
```
if (lastReceivedOffset.get(tp) == null && !unpolledPartitions.contains(tp)) {
log.info("When polling offsets, invalid offsets were detected. Resetting topic partition {}", tp);
resetOffsets(tp);
}
```
seek didn't update unpolledPartitions - reset offset uses default strategy to reset => seeks to the end
### Verifying this change
- [ ] Make sure that the change passes the CI checks.
*(Please pick either of the following options)*
This change is already covered by existing tests, such as KafkaApiTest.
### Does this pull request potentially affect one of the following parts:
*If `yes` was chosen, please highlight the changes*
No
### Documentation
- Does this pull request introduce a new feature? NO
3 files changed
