`TIMEDIFF` might give wrong result when casting values

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```
SELECT TIMEDIFF(CAST('2024-05-01' AS DATE), '2024-05-01 12:30:45');
SELECT TIMEDIFF(123456.789, 987654.321);
SELECT TIMEDIFF('12:34', '56:78');
SELECT TIMEDIFF('1.5:0:0', '3:0:0');
```

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

```
mysql> SELECT TIMEDIFF(CAST('2024-05-01' AS DATE), '2024-05-01 12:30:45');
+-------------------------------------------------------------+
| TIMEDIFF(CAST('2024-05-01' AS DATE), '2024-05-01 12:30:45') |
+-------------------------------------------------------------+
| NULL |
+-------------------------------------------------------------+
1 row in set (0.05 sec)

mysql> SELECT TIMEDIFF(123456.789, 987654.321);
+----------------------------------+
| TIMEDIFF(123456.789, 987654.321) |
+----------------------------------+
| NULL |
+----------------------------------+
1 row in set, 1 warning (0.01 sec)

mysql> SELECT TIMEDIFF('12:34', '56:78');
+----------------------------+
| TIMEDIFF('12:34', '56:78') |
+----------------------------+
| NULL |
+----------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SELECT TIMEDIFF('1.5:0:0', '3:0:0');
+------------------------------+
| TIMEDIFF('1.5:0:0', '3:0:0') |
+------------------------------+
| -02:59:58.5 |
+------------------------------+
1 row in set, 1 warning (0.00 sec)
```

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

```
mysql> SELECT TIMEDIFF(CAST('2024-05-01' AS DATE), '2024-05-01 12:30:45');
+-------------------------------------------------------------+
| TIMEDIFF(CAST('2024-05-01' AS DATE), '2024-05-01 12:30:45') |
+-------------------------------------------------------------+
| -12:30:45 |
+-------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT TIMEDIFF(123456.789, 987654.321);
+----------------------------------+
| TIMEDIFF(123456.789, 987654.321) |
+----------------------------------+
| 12:34:56.789 |
+----------------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SELECT TIMEDIFF('12:34', '56:78');
+----------------------------+
| TIMEDIFF('12:34', '56:78') |
+----------------------------+
| 12:34:00 |
+----------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SELECT TIMEDIFF('1.5:0:0', '3:0:0');
+------------------------------+
| TIMEDIFF('1.5:0:0', '3:0:0') |
+------------------------------+
| -02:59:58 |
+------------------------------+
1 row in set, 1 warning (0.00 sec)
```

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