Remove create_volume & create_volume_type methods

As tempest.scenario.manager was announced stable interface in Tempest 27.0.0[1] it can be now reused in plugins.

Replaced methods:
	* create_volume
	* create_volume_type

Etherpad concerning this effort:
https://etherpad.opendev.org/p/tempest-scenario-manager-cleanup

[1] https://docs.openstack.org/releasenotes/tempest/v27.0.0.html#release-notes-27-0-0

Change-Id: I183a0f8190bf7f336370732d8d08d1bb28ad2835
2 files changed