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/api/helpers/users/delete-related.js

@@ -21,10 +21,6 @@ module.exports = {
       userIdOrIds = sails.helpers.utils.mapRecords(inputs.recordOrRecords);
     }
 
-    await IdentityProviderUser.qm.delete({
-      userId: userIdOrIds,
-    });
-
     await Session.qm.delete({
       userId: userIdOrIds,
     });