The result of Upper() and Lower() are different with MySQL.

## Bug Report

### 1. Minimal reproduce step (Required)

```
create table t (a char(10) collate utf8mb4_bin);
insert into t values ('ꮑ');
select upper(a) from t;
```

### 2. What did you expect to see? (Required)

```
mysql> select upper(a) from t;
+----------+
| upper(a) |
+----------+
| ꮑ |
+----------+
1 row in set (0.00 sec)
```

### 3. What did you see instead (Required)
```
mysql> select upper(a) from t;
+----------+
| upper(a) |
+----------+
| Ꮑ |
+----------+
1 row in set (0.00 sec)
```

### 4. What is your TiDB version? (Required)

```
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version() |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v5.5.0-alpha-381-g2ede6a35b
Edition: Community
Git Commit Hash: 2ede6a35b83832b149ba5ce026680a18e9518ee7
Git Branch: master
UTC Build Time: 2022-02-21 10:28:59
GoVersion: go1.17.2
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
```