CBQE-611: test should fail if compaction didn't start

Change-Id: I4beb51b1197720a598519207c7e94961bbae4836
Reviewed-on: http://review.couchbase.org/24176
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: buildbot <build@couchbase.com>