fix(clickhouse): ensure that ALL and DISTINCT are rendered for except and intersect

[cpcloud]

Closes #4005.

[georgesittas]

Thanks!

[georgesittas]

@cpcloud I think there's actually an issue here:

>>> import sqlglot
>>> sqlglot.parse_one("""
... SELECT * FROM CTE1
... EXCEPT
... SELECT * FROM CTE2
... """, "clickhouse").sql("clickhouse")
'SELECT * FROM CTE1 EXCEPT DISTINCT SELECT * FROM CTE2'

EXCEPT without DISTINCT is, as I think you mentioned, EXCEPT ALL:

WITH CTE1 AS (
    SELECT 1 AS id, 'Alice' AS name
    UNION ALL
    SELECT 2 AS id, 'Bob' AS name
    UNION ALL
    SELECT 3 AS id, 'Charlie' AS name
    UNION ALL
    SELECT 4 AS id, 'Diana' AS name
    UNION ALL
    SELECT 5 AS id, 'Eve' AS name
    UNION ALL
    SELECT 1 AS id, 'Alice' AS name
),
CTE2 AS (
    SELECT 3 AS id, 'Charlie' AS name
    UNION ALL
    SELECT 4 AS id, 'Diana' AS name
    UNION ALL
    SELECT 6 AS id, 'Frank' AS name
)

-- Produces [(1, 'Alice'), (2, 'Bob'), (1, 'Alice'), (5, 'Eve')]
SELECT * FROM CTE1
EXCEPT
SELECT * FROM CTE2;

[georgesittas]

Fixed in #4009