CBQE-0: Fix for hanging compaction test

Change-Id: I1e52200d73a74425dc27eb0d69a9b8ad70a208a0
Reviewed-on: http://review.couchbase.org/40528
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Reviewed-by: Meenakshi Goel <meenakshi.goel@globallogic.com>
Tested-by: Meenakshi Goel <meenakshi.goel@globallogic.com>