Can't find a proper physical plan using READ_FROM_STORAGE hint and fts filter

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```sql
create table tt(a int primary key, b varchar(100));
alter table tt add fulltext index(b);
alter table tt set tiflash replica 2;
explain select /*+ READ_FROM_STORAGE(TIFLASH[tt]) */ count(*) from tt where match(b) against ('china' in boolean mode);
-- ERROR 1815 (HY000): Internal : Can't find a proper physical plan for this query

explain select count(*) from tt where match(b) against ('china' in boolean mode);
-- ERROR 1105 (HY000): Full text search can only be used with a matching fulltext index or you write it in a wrong way

```

### 2. What did you expect to see? (Required)
success
### 3. What did you see instead (Required)
ERROR 1815 (HY000): Internal : Can't find a proper physical plan for this query
### 4. What is your TiDB version? (Required)

feature/fts branch