Project-koku/koku-metrics-operator: koku-metrics-operator: service-account client credentials sent to user-controlled token_url

A flaw was found in koku-metrics-operator. The operator's CostManagementMetricsConfig custom resource allows a user able to edit the CR to specify an arbitrary OAuth token endpoint. When authentication.type is set to service-account, the operator sends the tenant's Red Hat SSO client_id and client_secret to this user-controlled URL, allowing the attacker to obtain the credentials.