refactor: tests

Author: alkatrivedi

samples/system-test/spanner.test.js

@@ -678,7 +678,7 @@ describe('Autogenerated Admin Clients', () => {
   // isolation_level_option
   it('should run read-write transaction with isolation level option set', () => {
     const output = execSync(
-      `node snapshot-isolation.js ${INSTANCE_ID} ${DATABASE_ID} ${PROJECT_ID}`
+      `node repeatable-reads.js ${INSTANCE_ID} ${DATABASE_ID} ${PROJECT_ID}`
     );
     console.log(output);
     assert.match(