Currently the tempest tests for the feature project default volume type[1] is pending because of lack of RBAC testing framework on tempest side.
Recently tempest added support for RBAC but still the alternate admin role was required for these tests which is added by[2]
All this code can be consumed by cinder tempest plugin when the next tempest is released since cinder-tempest-plugin gates use pinned version (last stable release) of tempest

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1465964
[2] https://review.opendev.org/c/openstack/tempest/+/773177