CBQE-0: fix offline_cluster_upgrade_non_default_path

remove data_path, index_path before their creation

Change-Id: I11de62ba1d67b0d23a90f3bb4684e23b2b8bc92a
Reviewed-on: http://review.couchbase.org/26911
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>