DefragmenterTest: Fix missing populate phase
DefragmenterTest: Fix missing populate phase

During previous migration of the Defragmenter benchmark tests to
GTest, we inadvertantly lost the actual population of the data they
need to act on. As such the various tests (Visit, DefragAlways,
DefragAge10, DefragAge10_20ms) essentially were invalid.

Fix this by restoring a populateVbucket() call.

Change-Id: Ib2c1d4b4385c4aa5b4611e034d80fffa0d7aaf54
Reviewed-on: http://review.couchbase.org/75872
Reviewed-by: Manu Dhundi <158873d90a7ef40f3637a222b7329c09d0222554@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

membase/ep-engine,membase/ep-engine,membase/ep-engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,membase/ep-engine,couchbase/ep-engine,daverigby/kv_engine,couchbase/ep-engine,couchbase/ep-engine,couchbase/ep-engine