the select clause after union all has many same name columns needn't use different aliases

### Is your feature request related to a problem or challenge?

now it reports an error
```sql
> select 1 a,2 b union all select null,null;
Error during planning: Projections require unique expression names but the expression "NULL" at position 0 and "NULL" at position 1 have the same name. Consider aliasing ("AS") one of them.
> select 1 a,2 b union all select 2,2;
Error during planning: Projections require unique expression names but the expression "Int64(2)" at position 0 and "Int64(2)" at position 1 have the same name. Consider aliasing ("AS") one of them.
```

### Describe the solution you'd like

It runs as normal
the result of above query equals to `select 1 a,2 b union all select null,null c` and` select 1 a,2 b union all select 2,2 c`

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

Start by reproducing the two SQL UNION ALL examples in the issue and inspect the planning path that rejects duplicate expression names. Done means both queries run without requiring aliases and produce the stated results.

Written by the indexing model from the issue text.