Fix segmented export functionality

What does this MR do and why?

While creating the export parts, we are iterating over all the vulnerability_reads records ordered by traversal_ids and vulnerability_id. This means a higher value can be set as start_id than end_id.

For example for the the following tuples;

('{9970}', 10), ('{9970}', 11), ('{9970, 9972}', 1)

The start_id will be 10 and the end_id will be 1 as these records are first sorted by traversal_ids.

For this reason, we need to compare the records by both traversal_ids and vulnerability_id while iterating over the records of the export part.

Database review

Here is the new query to iterate over vulnerability_reads records for given export part;

SELECT
    "vulnerability_reads".*
FROM
    "vulnerability_reads"
WHERE
    "vulnerability_reads"."traversal_ids" >= '{9970}'
    AND "vulnerability_reads"."traversal_ids" < '{9971}'
    AND "vulnerability_reads"."archived" = FALSE
    AND ("vulnerability_reads"."traversal_ids",
        "vulnerability_reads"."vulnerability_id") >= ('{9970}',
        535)
    AND ("vulnerability_reads"."traversal_ids",
        "vulnerability_reads"."vulnerability_id") <= ('{9970,12345}',
        585)
    AND (("vulnerability_reads"."traversal_ids",
            "vulnerability_reads"."vulnerability_id") > ('{9970}',
            6538))
ORDER BY
    "vulnerability_reads"."traversal_ids" ASC,
    "vulnerability_reads"."vulnerability_id" ASC
LIMIT 1000

https://console.postgres.ai/gitlab/gitlab-production-main/sessions/29279/commands/91071