Always setup the service with predictable name

This encapsulates the SUSE-oddity inside the definition and
simplifies the recipe in the api.
Always enable boot.lvm on Cinder-volume nodes

For LVM backend, we need lvm auto-activation to be running on
boot, otherwise cinder volumes are dead after a reboot of the
node. This is disabled on SLES by default, so we need to
activate the appropriate boot script.