CBQE-1119: sleep 5 sec after rest.force_eject_node

Change-Id: I8e4207eed29e1da72bef74bfe57f7c273b190d65
Reviewed-on: http://review.couchbase.org/26129
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>