Prefix `utils.get_root_helper` with underscore
Prefix `utils.get_root_helper` with underscore

This function is internal to `utils` so should be begin with an underscore to
clarify that it's private.

Change-Id: I6fdb0c7d46867347d74b79ec1ed5749ef597258a

openstack/oslo.versionedobjects,citrix-openstack-build/oslo.versionedobjects