CBQE-0: skip autocompaction settings for 1.8.1 upgrade

Change-Id: I25ed8f6b74c3200c6f0ee882064d21fd06711852
Reviewed-on: http://review.couchbase.org/26406
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>