Fix check_seeds macro

[aalan3]

We need to go through some tests and see if they are still correct. This type of error is very subtle since NULL = false in SQL becomes just NULL.

[aalan3]

@0xRobin do you have any insight on this? (since you worked on this previously in #3676). I think the legacy version of this check result_model = expected_seed should have resulted in pretty much the same issue.

[0xRobin]

ah yes you're right, the check is not null-safe (just as the equality operator is not).
I propose we follow trino docs here and start using the null-safe IS DISTINCT FROM or IS NOT DISTINCT FROM
https://trino.io/docs/current/functions/comparison.html#is-distinct-from-and-is-not-distinct-from
(as well as changing the legacy version to use <=>, the spark equivalent)
https://spark.apache.org/docs/3.0.0-preview/sql-ref-null-semantics.html#comparision-operators-

We might have missed some issues without knowing due to this.
Might be best to do a full test run on spark and trino to see if we have failing tests?

[aalan3]

Yes we should do a full test run to try to find issues. We currently only test when something is changed but we can do a full test in CI.

I'll do a separate PR for legacy since CI is breaking here.