Enable Kafka consumer offset committing

Enable Kafka consumer offset committing

It appears that reactor-kafka is setting auto.commit property to false,
which makes our CSITs fail nondeterministically due to automatic reset of
consumer offset.

By acknowledging manually, we will mark every message for committing,
which will be performed according to ConsumerConfiguration.
This way, Kafka broker should persist consumer offset.

Change-Id: I0c5156ff8df9bb3341e733e50a3c6866fdd94976
Issue-ID: DCAEGEN2-1495
Signed-off-by: Filip Krzywka <filip.krzywka@nokia.com>