MB-21646: Must wait for flushing to assert item counts
MB-21646: Must wait for flushing to assert item counts

The test uses the dcp-takeover estimate which is built from vb
curr_items, which is updated as part of flushing (for full_eviction).

Change-Id: Icb9c2a12b333f8b268d0abde287352cef0885d11
Reviewed-on: http://review.couchbase.org/70896
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

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