MB-10463 Correct the rep cursor position of UPR client.

This change fixes the bug in registering the UPR replicaiton
cursor, so that the cursor can start with the item whose seq
number > start_seqno passed.

Change-Id: Ie2d87f872abb025f587fa4c40b0f64bd8724e0d7
Reviewed-on: http://review.couchbase.org/34485
Reviewed-by: abhinav dangeti <abhinav@couchbase.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>