[Bug] In version 1.3.3 of IoTDB, The trend calculation function DIFF does not correctly handle the non-ignore null-value attribute.

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/iotdb/issues) and found nothing similar.

### Version

version 1.3.3 (Build: ad95a7e)

### Describe the bug and provide the minimal reproduce step

```
DROP DATABASE root.db0.t1
CREATE DATABASE root.db0.t1

CREATE TIMESERIES root.db0.t1.c0 WITH datatype=INT32;
INSERT INTO root.db0.t1(timestamp, c0) VALUES (1641024000000, 0), (1641024005000, null), (1641024010000, 2), (1641024015000, 3), (1641024020000, null);
CREATE TIMESERIES root.db0.t1.c1 WITH datatype=INT32;
INSERT INTO root.db0.t1(timestamp, c1) VALUES (1641024000000, 0), (1641024005000, 1), (1641024010000, 2), (1641024015000, 3), (1641024020000, 4);

# query 1
select DIFF(c0) from root.db0.t1;

# query 2
select DIFF(c0, 'ignoreNull'='false') from root.db0.t1;
```

### What did you expect to see?

The expected result set for Query 1 is: **null, 2, 1**

The expected result set for Query 2 is: **null, null, null, 1, null**

### What did you see instead?

The actual result set returned by Query 1 is: **null, 2, 1**

The actual result set returned by Query 2 is: **null, 2, 1**

### Anything else?

Dear IoTDB team, In the above trend calculation function queries, Query 1 uses the `DIFF` function with the **ignore null-value** attribute enabled, while Query 2 has it disabled. However, the results returned by Query 2 indicate that null-value data was not included in the trend calculation, which does not meet expectations.

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Bắt đầu bằng cách chạy các truy vấn tái hiện tối thiểu cho DIFF trên IoTDB 1.3.3 và xác định phần triển khai hàm DIFF cùng các kiểm thử hiện có của nó. So sánh hành vi khi ignoreNull được bật và tắt; hoàn tất khi Query 2 trả về null, null, null, 1, null trong khi Query 1 vẫn trả về null, 2, 1.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.