Use common code instead of novaclient.utils

Module `novaclient.utils` contains a lot of functions which are
presented in modules from common code.

* service_type -> novaclient.openstack.common.cliutils.service_type
* get_service_type -> novaclient.openstack.common.cliutils.get_service_type
* pretty_choice_list ->
      novaclient.openstack.common.cliutils.pretty_choice_list
* import_class -> oslo.utils.importutils.importclass
* HookableMixin -> novaclient.openstack.common.apiclient.base.HookableMixin

Change-Id: Ia6cac058da12c852d92f26875a66ae31cc4c63d4
Merge "Use common code instead of novaclient.utils"