'select from values' returns error:Unknown table ''

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
```
select * from (values row(1),row(2)) a;
```

### 2. What did you expect to see? (Required)
results from mysql:
```
MySQL [fuzztest]> select * from (values row(1),row(2)) a
-> ;
+----------+
| column_0 |
+----------+
| 1 |
| 2 |
+----------+
2 rows in set (0.00 sec)

```

### 3. What did you see instead (Required)
```
MySQL [test1]> select * from (values row(1),row(2)) a
-> ;
ERROR 1051 (42S02): Unknown table ''
```

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

```
MySQL [test1]> select tidb_version();
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version() |
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v7.5.6
Edition: Community
Git Commit Hash: 1ad553d6de2cb0c9b2f3cfdb760aaae109b2c466
Git Branch: HEAD
UTC Build Time: 2025-03-12 10:49:51
GoVersion: go1.21.13
Race Enabled: false
Check Table Before Drop: false
Store: tikv |
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.07 sec)
```

Start by running the reported SELECT query on TiDB v7.5.6 and compare its behavior with the MySQL result shown in the issue. Trace the handling of a VALUES expression used as a derived table, then verify that the query returns two rows without the Unknown table error.

Written by the indexing model from the issue text.