Change scheduler for JDBC interpreter to use concurrent execution

JDBCInterpreter:
  @Override
  public Scheduler getScheduler() {
    return SchedulerFactory.singleton().createOrGetFIFOScheduler(
        JDBCInterpreter.class.getName() + this.hashCode());
  }

HiveInterpreter:
  @Override
  public Scheduler getScheduler() {
    return SchedulerFactory.singleton().createOrGetParallelScheduler(
        HiveInterpreter.class.getName() + this.hashCode(), 10);
  }