Internal Error: Cannot found physical plan

## Bug Report

### 1. Minimal reproduce step (Required)

```sql
create table t (a int, b int);
alter table t set tiflash replica 1;
set @@tidb_allow_mpp=0;
SELECT SLEEP(5);
select /*+ READ_FROM_STORAGE(TIFLASH[t]) */ a from t; -- ERROR 1815 (HY000): Internal : Can't find a proper physical plan for this query
```
### 2. What did you expect to see? (Required)
No error

### 3. What did you see instead (Required)
Internal error.
The `SELECT SLEEP(5);` is necessary to trigger this issue.

### 4. What is your TiDB version? (Required)
```
| Release Version: v7.3.0
Edition: Community
Git Commit Hash: 40b72e7a9a4fc9670d4c5d974dd503a3c6097471
Git Branch: heads/refs/tags/v7.3.0
UTC Build Time: 2023-08-08 10:08:14
GoVersion: go1.20.7
Race Enabled: false
Check Table Before Drop: false
Store: tikv |
```

Startup command:
```shell
tiup playground 7.3.0
```