Tombstone pipeline - investigate why TEDs failed to migrate during prelim dry run

Target DB dump and the exported corp_processing table with migrated TINGs have been uploaded to the usual project in GCP cloud storage under the "corp_migration_misc" bucket. Use this as starting point for migrating TEDs.

- [ ] investigate issue
- [ ] fix issue if small, otherwise cut another ticket

Start with the target DB dump and exported corp_processing table in the corp_migration_misc bucket in GCP cloud storage. Investigate why TEDs failed to migrate during the preliminary dry run and determine whether the fix is small enough to make here; otherwise, document the findings in a follow-up ticket.

Written by the indexing model from the issue text.