Query with Contradictory ON and HAVING Conditions Incorrectly Returns Rows

## Bug Report
Hi, TiDB developers. Thanks for reading my report.

A bug has been identified where a `LEFT JOIN` query with logically contradictory conditions in the `ON` and `HAVING` clauses incorrectly returns rows when combined with a complex `WHERE NOT CASE` expression.

### 1. Minimal reproduce step (Required)
[test.sql](https://github.com/user-attachments/files/23848824/test.sql)
```sql
CREATE TABLE t0(c0 CHAR );
CREATE TABLE t1 LIKE t0;
INSERT INTO t1 VALUES ('');
INSERT INTO t0(c0) VALUES ('_');

SELECT * FROM t1 LEFT JOIN t0 ON t1.c0 LIKE t0.c0 WHERE NOT (CASE true WHEN true THEN t0.c0 WHEN false THEN (t0.c0)REGEXP('_') END) HAVING t1.c0 NOT LIKE t0.c0;
+------+------+
| c0 | c0 |
+------+------+
|  | _ |
+------+------+
1 row in set, 1 warning (0.01 sec)

SELECT * FROM t1 LEFT JOIN t0 ON t1.c0 LIKE t0.c0 WHERE true HAVING t1.c0 NOT LIKE t0.c0;
empty set
```

### 2. What did you expect to see? (Required)
```sql
SELECT * FROM t1 LEFT JOIN t0 ON t1.c0 LIKE t0.c0 WHERE NOT (CASE true WHEN true THEN t0.c0 WHEN false THEN (t0.c0)REGEXP('_') END) HAVING t1.c0 NOT LIKE t0.c0;
empty set
```

### 3. What did you see instead (Required)
```sql
SELECT * FROM t1 LEFT JOIN t0 ON t1.c0 LIKE t0.c0 WHERE NOT (CASE true WHEN true THEN t0.c0 WHEN false THEN (t0.c0)REGEXP('_') END) HAVING t1.c0 NOT LIKE t0.c0;
+------+------+
| c0 | c0 |
+------+------+
|  | _ |
+------+------+
1 row in set, 1 warning (0.01 sec)
```
### 4. What is your TiDB version? (Required)

| Release Version: v8.5.4
Edition: Community
Git Commit Hash: https://github.com/pingcap/tidb/commit/e4e814fdc0afe9c3a6e5e96f129d83df802ab820
Git Branch: HEAD
UTC Build Time: 2025-11-26 15:53:39
GoVersion: go1.23.12
Race Enabled: false
Check Table Before Drop: false
Store: tikv |