Fix test_stamp_pattern to remove dependency of user supplied volume name

This patch removes CONF.compute.volume_device_name dependency and
use modified list_disks method to get the newly attached
device name and use that for mkfs rather than the user supplied
device name which is based on assumtion.

Also modfied test_attach_detach testcase and unit test
for remote_client accordingly.

Change-Id: I862d1ba55f45b09385057a51b0b52a851c19287e
Closes-Bug: #1852807
5 files changed