MB-7629 Remove unused variable

Change-Id: Idedec34ecb4b968b6378c5fd16d53e63dca6c07c
Reviewed-on: http://review.couchbase.org/25601
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Reviewed-by: Fulu Li <fulu@couchbase.com>
Tested-by: Filipe David Borba Manana <fdmanana@gmail.com>