Some tests incorrectly override configuration values

[Alex Meade]

Some tests use setattr and delattr to override configuration values for a test. This is unnecessary since test.TestCase utilizes teh CONF.set_override functionality in oslo common. It is also dangerous since values may not be unset correctly.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/75980

[Openstack Gerrit (openstack-gerrit)]

Reviewed: https://review.openstack.org/75980
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=f72c547dbaa41b82ff243f0407cffc39a23424f7
Submitter: Jenkins
Branch: master

commit f72c547dbaa41b82ff243f0407cffc39a23424f7
Author: Alex Meade <email address hidden>
Date: Mon Feb 24 15:28:23 2014 -0500

    Update tests to use CONF.set_override

    This patch updates some tests that were overriding configuration
    values by means other than CONF.set_override. It also removes any
    left over references to the glusterfs_disk_util config option.

    Closes-bug: 1284293
    Closes-bug: 1284300

    Change-Id: Id2d14cc3ff77322d017033f3558aed9cd637589b