MB-6983: omitted isBytes flag for water mark values

Change-Id: I3742ff621ce4af40f0fb1609f0fbfb929292a832
Reviewed-on: http://review.couchbase.org/33402
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>