fix(internet): a truncated IGMPv3 Report falls back to Raw instead of parsing what it carries #2650

While #2618 was being written, an IGMPv3 Membership Report cut short by the capture fell back to Raw with the error "Field records has an item that consumed no data". It did not parse as IGMPv3 with a truncated record list, so no checksum_status is recorded for it. An IGMPv3 Query cut the same way parses. This is older behaviour, not something #2618 introduced. The worker observed it, and it has not yet been reproduced independently.

Expected: a Report whose record list is cut short parses as far as its octets go and is marked truncated, as other list-bearing schemas are. It should not refuse the whole layer.

To do: reproduce on main, find where the record-list field refuses a zero-length item, and fix that at the source. Cover a Report cut inside a record header and a Report cut inside a source list.