`PERIOD_DIFF` failed to validate incorrect argument

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

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

```
mysql> SELECT PERIOD_DIFF('\n202405\n', '\t202406');
ERROR 1210 (HY000): Incorrect arguments to period_diff
```

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

```
mysql> SELECT PERIOD_DIFF('\n202405\n', '\t202406');
+---------------------------------------+
| PERIOD_DIFF('\n202405\n', '\t202406') |
+---------------------------------------+
| -1 |
+---------------------------------------+
1 row in set (0.00 sec)
```

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