Geo: Fix generate-blob-replicator script for upload partition mode

What does this MR do and why?

Geo: Fix generate-blob-replicator script for upload partition mode

Fix two bugs affecting --upload-partition mode:

• Replicator include indentation was misaligned for the UploadReplicatorBehavior concern (12 spaces instead of 4), producing invalid Ruby.
• Factory parent model name derivation was incorrect for models where the factory name differs from the derived name (e.g. Projects::Topic has factory :topic, not :project_topic). Added --parent-factory CLI option to allow overriding.

Relates to: #598863 (closed)

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Check out this branch and run the script in dry-run mode to verify it parses correctly:

   ruby scripts/geo/generate-blob-replicator \
     --replicable-name=project_topic_upload \
     --model-class='Projects::Topic' \
     --table-name=project_topic_uploads \
     --sharding-key=organization_id \
     --milestone=19.0 \
     --upload-partition \
     --parent-factory=topic \
     --dry-run

2. Run without --dry-run and verify the indentation fix — the generated replicator should have 4-space indentation:

   grep -A1 'BlobReplicatorStrategy' ee/app/replicators/geo/project_topic_upload_replicator.rb

   Expected:

       include ::Geo::BlobReplicatorStrategy
       include ::Geo::Concerns::UploadReplicatorBehavior

3. Verify the --parent-factory option works — the generated factory and spec should use :topic, not :project_topic:

   grep 'create(:' ee/spec/factories/geo/project_topic_upload.rb
   grep 'create(:topic' ee/spec/models/geo/project_topic_upload_spec.rb

4. Verify rubocop passes on the generated replicator (the indentation fix resolves the previous failure):

   bundle exec rubocop ee/app/replicators/geo/project_topic_upload_replicator.rb

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #598863 (closed)