We need some tests against other bucket types

One attempt at that is in couchbase/tests_v3/cases/admin_t.py. But, it is skipped as it doesn't work (uses old interface, but probably there's more there than just that). Ideally we would look at what is there, come up with a separate test for that (and more, ideally than just that). And then refactor that admin_t test (and perhaps admin itself), trimming out things we no longer use.

The 2 tasks go together, so it is one ticket. We can always make a second if you do it one at a time...