content in database cannot be completely cleared

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```sql
create or replace view `test`.`V` as (select 1);

create or replace view `test`.`v` as (select 1);

drop database test;

create database test;

show tables in test;
```

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

the database `test` should be empty because it was dropped & recreated.

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

- the first time I execute the SQLs, there is one view `V` left
- the second time, there are two
- and the third time, there are three

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

```
Release Version: v8.5.1
Edition: Community
Git Commit Hash: fea86c8e35ad4a86a5e1160701f99493c2ee547c
Git Branch: HEAD
UTC Build Time: 2025-01-16 07:40:13
GoVersion: go1.23.2
Race Enabled: false
Check Table Before Drop: false
Store: tikv
```