CBQE-0: remove redundant test case and increase timeout for
load_with_failover test after async delete ops

Change-Id: If47d261c0f076e0b1a12ece072ff29e811031e0a
Reviewed-on: http://review.couchbase.org/31013
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>