Geo: Replicate Dependencies::DependencyListExport::Part uploads

What does this MR do and why?

Adds Geo SSF (self-service framework) replication and verification for the dependency_list_export_part_uploads partition table so Dependencies::DependencyListExport::Part attachments are mirrored from the primary to secondary Geo sites alongside the other upload partitions.

Generated with scripts/geo/generate-blob-replicator:

scripts/geo/generate-blob-replicator \
  --replicable-name=dependency_list_export_part_upload \
  --model-class=Dependencies::DependencyListExport::Part \
  --table-name=dependency_list_export_part_uploads \
  --sharding-key=organization_id \
  --milestone=19.2 \
  --upload-partition

The registry and state index names were shortened to the idx_dlep_upl_* convention to stay within PostgreSQL's 63-character identifier limit, matching the sibling vulnerability_export_part_upload tables.

References

• Closes #589908 (closed)
• Parent epic: &20933

How to set up and validate locally

Requires a primary + secondary Geo setup (e.g. two GDKs).

1. On both sites, run migrations:

   bin/rake db:migrate db:migrate:geo

2. On the primary, enable replication:

   Feature.enable(:geo_dependency_list_export_part_upload_replication)

3. Generate a group-level dependency list export on the primary that is large enough to be split into parts (each part writes an attachment to dependency_list_export_part_uploads).

4. On the secondary, confirm the registry row was created and replication + verification succeeded:

   Geo::DependencyListExportPartUploadRegistry.last => state: 'synced', verification_state: 'succeeded'

5. Confirm the file is present at the secondary's upload path and that verification_checksum matches the primary's.

6. Optionally re-verify:

   Geo::DependencyListExportPartUploadRegistry.last.verification_pending!

MR acceptance checklist

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