Removing test_duration variable from bench/consumer.py
Removing test_duration variable from bench/consumer.py

Variable test_duration is not necessary and we can use conf.time directly
 in the actual parameters.

Change-Id: I2747a300ae0c4155e1f50aad31ac88f6510753bd
Closes-Bug: #1361302

openstack/zaqar,openstack/zaqar,openstack/zaqar,openstack/zaqar