SHOW statements: LIKE clause (ci) vs WHERE clause (bin) case-sensitivity split

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```
CREATE TABLE SHOWTEST_upper(v INT);
CREATE TABLE showtest_lower(v INT);
SHOW TABLES LIKE 'SHOW%'; -- 2 rows (ci)
SHOW TABLES WHERE Tables_in_hunt LIKE 'SHOW%'; -- 1 row (bin)
```
### 2. What did you expect to see? (Required)
```
mysql> SHOW TABLES LIKE 'SHOW%'; -- 2 rows (ci)
+-------------------------+
| Tables_in_chqin (SHOW%) |
+-------------------------+
| SHOWTEST_upper |
+-------------------------+
1 row in set (0.00 sec)

```
### 3. What did you see instead (Required)
```
mysql> SHOW TABLES LIKE 'SHOW%'; -- 2 rows (ci)
+-------------------------+
| Tables_in_chqin (SHOW%) |
+-------------------------+
| SHOWTEST_upper |
| showtest_lower |
+-------------------------+
2 rows in set (0.00 sec)
```
### 4. What is your TiDB version? (Required)

```
mysql> select tidb_version();
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version() |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v9.0.0-beta.2.pre-2174-g65ac2fad58-dirty
Edition: Community
Git Commit Hash: 65ac2fad582510b92d3c4b79999e48217c989737
Git Branch: master
UTC Build Time: 2026-08-30 15:18:00
GoVersion: go1.25.12
Race Enabled: false
Check Table Before Drop: false
Store: unistore
Kernel Type: Classic |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
```