Add tests for IN-list filter pruning and NOT filter behavior

[alxmrs]

Problem

The TestFilterPushdown suite is missing coverage for two cases:

1. IN-list pruning

The Rust in_list_excludes() method is implemented but never exercised by tests. A test should verify that WHERE dim IN (v1, v2) prunes partitions where none of v1, v2 fall within the partition range.

Example: 4 time partitions, WHERE time IN ('2020-01-05', '2020-01-10') should read only partition 0.

2. NOT filter behavior

The Expr::Not arm previously had a correctness bug (now fixed). A regression test should verify:

• NOT (col > X) correctly includes partitions containing values ≤ X
• NOT (col < X) correctly includes partitions containing values ≥ X

Why now

Adding these tests serves as a regression guard to confirm that the Expr::Not fix remains correct and that IN-list pruning works as advertised. Without them, future changes to the pruning logic could silently regress.