CBQE-0: fix autocompaction test

Change-Id: I0ab959eca6b7942b07cbc4a833cabb3401703b9e
Reviewed-on: http://review.couchbase.org/28737
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>