Testing against MinIO doesn't restrict permissions

[omus]

In #287 we updated the testsets to use narrowly scoped roles to ensure that we were only using required permissions for each testset. This ensures that the documented permissions for each function provided by AWSS3 only uses the permissions it states it needs. However, that PR didn't setup access control for MinIO. We should be able to setup something similar for MinIO so those tests respect the required permissions:
https://min.io/docs/minio/kubernetes/upstream/administration/identity-access-management/policy-based-access-control.html