MB-100: minor changes in logs in rebalance+compaction

Change-Id: I88db56115005ce0bef8f8c6e3121b9e27aa23fa1
Reviewed-on: http://review.couchbase.org/24193
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>