Require member role in the static get_primary_creds

otherwise the reader role might be picked up, which is not enough
in some cases even when scope and new policies are not enforced,
like barbican requiring a 'creator' role,
and reader+creator makes no sense.

Change-Id: Icab8c2a84d13ba29e4402442edc29df539c70c9f
Related-Issue: PRODX-26490
2 files changed