Ingestion checks

The ingestion script should be modified to do the following:
- [ ] Modify the ingestion script to change "the [Tt]he" → "the" in any book title
- [ ] Modify the aclpub2 format checking script to complain about "the the" (case insensitive)

_Originally posted by @mjpost in https://github.com/acl-org/acl-anthology/pull/5676#pullrequestreview-3093585101_

Locate the ingestion script and the aclpub2 format checking script, then inspect their existing title handling and validation entry points. Done means book titles are normalized from "the the" to "the" with the stated capitalization behavior, and the checker reports case-insensitive "the the" occurrences.

Rédigé par le modèle d'indexation à partir du texte de l'issue.