Avoid rendering parentheses on left associative operations

There exist a few operations that are left associative, where we still render unnecessary parentheses, e.g. `Field::sub` or `Field::div`:

```sql
-- These are equivalent:
((((0 - 1) - 2) - 3) - 4)
0 - 1 - 2 - 3 - 4

-- These aren't equivalent
(0 - (1 - (2 - (3 - 4))))
0 - 1 - 2 - 3 - 4
```

This affects at least:

- [x] `SUB`
- [x] `DIV`

Possibly others, as well