CBQE-0: force_eject_node if not all ejected nodes were cleaned successfully

http://qa.sc.couchbase.com/job/centos_x64--00_02-graceful-failover-P0/5/console

Change-Id: I29642263395e35468993785e46afdef0eaddcb43
Reviewed-on: http://review.couchbase.org/36220
Reviewed-by: Parag Agarwal <agarwal.parag@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>