Currently whenever we start a new C* session in the database plugin, we
run `LIST ALL` to determine whether we are a superuser, or otherwise
have permissions on roles. This is a fairly sensible way of checking
this, except it can be really slow when you have a lot of roles (C*
isn't so good at listing things). It's also really intensive to C* and
leads to a lot of data transfer. We've seen timeout issues when doing
this query, and can of course raise the timeout, but we'd probably
prefer to be able to switch it off.
ffb699e48c