Silence the 7 warnings reported by `cargo clippy --all --tests`:
- Replace manual `% n == 0` parity checks with `is_multiple_of`
(`manual_is_multiple_of`) in index_writer, doc_predicate_query and
seek_danger tests. `is_multiple_of` is stable for unsigned integers as
of 1.87, which matches the crate MSRV.
- Prefix the intentionally unused `other_segment_meta` binding with an
underscore. The binding is kept rather than dropped because the
inventory only tracks live `SegmentMeta`s, so dropping it would
invalidate the `inventory.all()` assertion in the same test.
No behavior change.
Co-authored-by: Paul Masurel <paul.masurel@datadoghq.com>