CBQE-0: clear logs when rebalance stuck in cbrecovery

Change-Id: Ib8510437ac5cd02749674ae95c82ad85618629fc
Reviewed-on: http://review.couchbase.org/33701
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>