[IT Tests] Message not acknowledged using Direct Runner

[damccorm]

When running integration tests using direct runner, the messages are not acknowledged. The function finalizeCheckpoint() is not called because the shard's checkpoint is always null.

!UnboundedReadEvaluatorFactory.java.png!

The acknowledgement is called inside of the function finalizeCheckpoint()

!JmsCheckpointMark.java.png!

Imported from Jira BEAM-14313. Original Jira may contain additional context.
Reported by: Amrane.