Use fernet in gates

we have gates currently broken due using rocky keystone code.
we have no way to test our release until we branch out queens.
this change doesnt change globals default, only our gates tests.

Change-Id: I189aa8cafc73a365668d79e4b186aac21da63a6f

tests/templates/globals-default.j2

@@ -36,3 +36,5 @@ enable_cinder: "yes"
 ceph_pool_pg_num: 64
 ceph_pool_pgp_num: 64
 {% endif %}
+
+keystone_token_provider: "fernet"