Add empty private_key_filename values as it is mandatory for an ssh operation

workbooks/service_initialize.yaml

@@ -349,6 +349,7 @@ workflows:
           host: localhost
           username: s3temp
           private_key: <% $.ssh_hack_key %>
+          private_key_filename: ""
         on-success:
           - update_s3_user
           - remove_temporary_role