MB-8861 Increase the number of vbucket / tap producer map locks

Change-Id: I858029642f69a8e6dae8349f8cd2a169396bcdb4
Reviewed-on: http://review.couchbase.org/28383
Reviewed-by: abhinav dangeti <abhinav.dangeti@gmail.com>
Tested-by: abhinav dangeti <abhinav.dangeti@gmail.com>