manage/unmanage volume/snapshot from truenas internal reference not yet supported

[databunnysg]

driver feature manage/unmanage volume/snapshot from truenas internal reference not yet supported

Failed tempest ci test case
https://docs.openstack.org/tempest/latest/_modules/volume/admin/test_snapshot_manage.html#SnapshotManageAdminTest
https://docs.openstack.org/tempest/latest/_modules/volume/admin/test_volume_manage.html#VolumeManageAdminTest.test_unmanage_manage_volume