MB-11405 optimize by avoiding string constructions

getDescription() overhead in performance is seen in profile
reports when large number of active buckets come into picture
Avoid constructing strings in it to optimize CPU

Change-Id: Ic2d1e875eba51a9dff3a2530ca4d3b0ffe5d1e0d
Reviewed-on: http://review.couchbase.org/38337
Tested-by: Sundararaman Sridharan <sundar@couchbase.com>
Reviewed-by: abhinav dangeti <abhinav@couchbase.com>