fix migrations

Author: Antoine de Chevigné

run/migrations/20250822091149-add-concurrent-indexe.js

@@ -17,12 +17,5 @@ module.exports = {
   },
 
   async down (queryInterface, Sequelize) {
-    await queryInterface.sequelize.query(`
-      DROP INDEX IF EXISTS blocks_orbit_batch_id_idx;
-    `);
-
-    await queryInterface.sequelize.query(`
-      DROP INDEX IF EXISTS transactions_block_id_idx;
-    `);
   }
 };