set session level `sql_require_primary_key` didn't check privilege

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```
mysql> CREATE USER 'test'@'%' IDENTIFIED BY '';
Query OK, 0 rows affected (0.027 sec)
```

```
$ mysql -u test -h 127.0.0.1 -P 4000
...
mysql> set sql_require_primary_key = 0;
Query OK, 0 rows affected (0.000 sec)

mysql> set global sql_require_primary_key = 0;
ERROR 1227 (42000): Access denied; you need (at least one of) the SUPER or SYSTEM_VARIABLES_ADMIN privilege(s) for this operation
```

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

both session and global level should fail. https://dev.mysql.com/doc/refman/8.4/en/server-system-variables.html#sysvar_sql_require_primary_key

### 3. What did you see instead (Required)

session level has no error

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

at least v8.5.2