Change CINDER_LVM_TYPE to 'auto' as the default
Change CINDER_LVM_TYPE to 'auto' as the default

This was previously set to thin as the default, but at the time
there were failures seen with what appeared to be race conditions
when creating snapshots.

These failures are not seen locally, and we have a lot of installs
using the default auto by this point with no reports from the field
of seeing this failure. This is to be able to more extensively test
this in the gate, and hopefully get this switched over to be able
to thinly provision by default when possible.

Change-Id: I3e99adadd1c37ba8b24b6cb71a8969ffc93f75a1
Related-bug: #1642111

dtroyer/devstack,noironetworks/devstack,dtroyer/devstack,group-policy/devstack,nawawi/openstack,openstack-dev/devstack,group-policy/devstack,noironetworks/devstack,openstack-dev/devstack,nawawi/openstack