MB-10875 Fix to a bug in updating the persistence cursor offset.

We should NOT set the persistence cursor offset to be equal to the
number of items including meta items after getting all the dirty
items, as we update the cursor offset while moving the cursor.

Change-Id: Ic80b3153ec7032a8d99d907db0a80e96fd3c5674
Reviewed-on: http://review.couchbase.org/36240
Reviewed-by: abhinav dangeti <abhinav@couchbase.com>
Tested-by: abhinav dangeti <abhinav@couchbase.com>