feat: Remove OIDC and SSO support

Existing SSO accounts have no local password, so the migration
deactivates them before dropping is_sso_user and the
identity_provider_user table.

server/config/policies.js

@@ -49,8 +49,6 @@ module.exports.policies = {
   'bootstrap/show': true,
   'terms/show': true,
   'access-tokens/create': true,
-  'access-tokens/exchange-with-oidc': true,
-  'access-tokens/debug-oidc': true,
   'access-tokens/accept-terms': true,
   'access-tokens/revoke-pending-token': true,
 };