Resolve "Failure in spec/ee/spec/services/ee/projects/hashed_storage/migrate_attachments_service_spec.rb"

What does this MR do?

Fixes an order-based spec failure when running:

bin/rspec spec/services/projects/hashed_storage/migrate_repository_service_spec.rb spec/ee/spec/services/geo/hashed_storage_attachments_event_store_spec.rb

What are the relevant issue numbers?

Closes #4242 (closed)

/cc @nick.thomas