Inconsistency between normal select and prepared statement query

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

In the following test case, the normal query returns `2`, but the prepared statement triggered an error `Unknown column '2' in 'group statement'`
```
CREATE TABLE t0(c0 DECIMAL);
INSERT IGNORE INTO t0 VALUES (1);
SELECT 2 FROM t0 WHERE t0.c0 GROUP BY 1; -- 2
SET @a = 2;
PREPARE prepare_query FROM 'SELECT ? FROM t0 WHERE t0.c0 GROUP BY 1';
EXECUTE prepare_query USING @a; -- Unknown column '2' in 'group statement'
DEALLOCATE PREPARE prepare_query;
```

### 2. What did you expect to see? (Required)
No error.

### 3. What did you see instead (Required)
`Unknown column '2' in 'group statement'`

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

```
tidb_version()
Release Version: v9.0.0-beta.2.pre-196-g312226f869\nEdition: Community\nGit Commit Hash: 312226f869d56922135e1c177cac6c90319c3134\nGit Branch: HEAD\nUTC Build Time: 2025-09-21 08:27:14\nGoVersion: go1.23.11\nRace Enabled: false\nCheck Table Before Drop: false\nStore: unistore\nKernel Type: Classic
```