Fix Style/OpenStructUse offenses

Changelog: other

.rubocop_todo/style/open_struct_use.yml

@@ -34,7 +34,6 @@ Style/OpenStructUse:
   - spec/helpers/profiles_helper_spec.rb
   - spec/initializers/doorkeeper_spec.rb
   - spec/lib/gitlab/auth/o_auth/provider_spec.rb
-  - spec/lib/gitlab/cleanup/orphan_lfs_file_references_spec.rb
   - spec/lib/gitlab/database/migrations/runner_spec.rb
   - spec/lib/gitlab/gitaly_client/blobs_stitcher_spec.rb
   - spec/lib/gitlab/gitaly_client/diff_stitcher_spec.rb

spec/lib/gitlab/cleanup/orphan_lfs_file_references_spec.rb

@@ -97,6 +97,6 @@ RSpec.describe Gitlab::Cleanup::OrphanLfsFileReferences do
   def stub_lfs_pointers(repo, *oids)
     expect(repo.gitaly_blob_client)
       .to receive(:get_all_lfs_pointers)
-      .and_return(oids.map { |oid| OpenStruct.new(lfs_oid: oid) })
+      .and_return(oids.map { |oid| double('pointers', lfs_oid: oid) })
   end
 end