change of openstack role api

Summary

As the refactor for the openstack role is planned, we will need to adjust this role too. After upgrading the openstack role, this role will not work.

Steps to reproduce

Simply upgrade openstack role version and run this role's device_from_openstack_volume action.

Expected behavior

filesystem_devices fact should be set.

Actual behavior

Probably the fatal error will occur - no openstack_instance_volume_attachments variable found.

Relevant logs and/or screenshots

Nope

Possible fixes

We should use the new api when the openstack#20 (closed) will be resolved.