fix sahara service-type

the sahara service-type is data-processing,not data_processing
if use data_processing,the sahara client will take mistake.
refer to [1]

[1] https://docs.openstack.org/sahara/latest/install/installation-guide.html#common-installation-steps


Co-Authored-By: zhulingjie <easyzlj@gmail.com>

Change-Id: I4c6704a81921bf713073451dc4e93e44234e5a7c