// If storage class is set using the env vars MINIO_STORAGE_CLASS_RRS and
// MINIO_STORAGE_CLASS_STANDARD or server config fields corresponding values are
// returned.
//
// -- if input storage class is empty then standard is assumed
//
// -- if input is RRS but RRS is not configured/initialized '-1' parity
//
//	for RRS is assumed, the caller is expected to choose the right parity
//	at that point.
//