MB-10702: Include the proper NRU bits in an UPR mutation

When sending an UPR mutation, we need to include the proper
NRU bits of the stored value.

Change-Id: If7fd01e34079161212cf213fb62cafefa9248f7c
Reviewed-on: http://review.couchbase.org/35897
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Chiyoung Seo <chiyoung@couchbase.com>