Currently the volume backup restore command returns with error
even though the restore is initiated.
This patch corrects the response received from SDK and processes
it in a human readable form.
Change-Id: I7f020631fbb39ceef8740775fd82686d90a6c703
Closes-Bug: #2063335
Depends-On: https://review.opendev.org/c/openstack/openstacksdk/+/931755