add wait_for_persistence() after extra access phase
add wait_for_persistence() after extra access phase

Change-Id: Ifc78e60c4a687cb5ea13456add08c7ff252466a0
Reviewed-on: http://review.couchbase.org/c/perfrunner/+/146748
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Korrigan Clark <11cf3ebdc6cba78053c91b2fd94cb21b47d0d02e@couchbase.com>

couchbase/perfrunner,couchbase/perfrunner,couchbase/perfrunner,couchbase/perfrunner,couchbase/perfrunner,couchbase/perfrunner