CBQE-0:: remove redundant test cases in negative test cases for failover

Change-Id: I5057b46eeed3f17b1ed54e26791042149e656471
Reviewed-on: http://review.couchbase.org/41149
Reviewed-by: Parag Agarwal <agarwal.parag@gmail.com>
Tested-by: Parag Agarwal <agarwal.parag@gmail.com>