change cinder image os type to ubuntu

The yaook cinder image was based on almalinux which randomly decided to upgrade qemu-img from 4.6 to 6.X. The 6.X version does not creates the netapp image cache before creating the volume. (https://github.com/qemu/qemu/commit/1c404d756fd59ecee09dec924b88c492d24b3fc8) We can not pin the version to 4.6 in almalinux because this version is not part of the repo anymore.