This is to fix secrets_manager.SecretsManager.get method which
is passing in the secret reference to Barbican directly for
GET /secrets/{uuid} [0] causing Barbican to raise a
ValueError exception when it attempts to validate that
{secret_uuid} is in fact a UUID.
The fix is to extract the secret_uuid from the secret_ref returned
by Barbican before querying the GET /secrets/{uuid} API.
[0] https://docs.openstack.org/barbican/latest/api/reference/secrets.html#get-v1-secrets-uuid
Change-Id: I4db317e3ba12b4268df5b84b79be8da1da5ac2ba
91de02be34