Manila: Disable consistency group tests
Manila: Disable consistency group tests

The two glusterfs drivers in Manila do not yet support consistency
groups feature. So disable the related Tempest tests during the
CI runs of the two drivers.

Change-Id: I07e860971451c4aa875272a34ebf845603f9f0be
Closes-Bug: #1498101

stackforge/devstack-plugin-glusterfs,stackforge/devstack-plugin-glusterfs