Federated OIDC Users Can Bypass externalGroupsWhitelist to Gain uaa.admin

A vulnerability allows users authenticating through a federated OIDC provider to obtain the uaa.admin scope despite operators restricting that provider through externalGroupsWhitelist configuration. The issue occurs specifically when an OIDC identity provider uses groupMappingMode: AS_SCOPES with a wildcard externalGroupsWhitelist entry.