Bulk download results/submissions: dead code in `submissions.py`

[Didayolo]

@ObadaS @nicomy
The following PR:

• Optimise download many #2001

Introduced useless lines of code in src/apps/api/views/submissions.py, in function download_many:

        for sub in submissions:
            file_path = sub.data.data_file.name.split('/')[-1]
            short_name = f"{sub.id}_{sub.owner}_PhaseId{sub.phase.id}_{sub.data.created_when.strftime('%Y-%m-%d:%M-%S')}_{file_path}"
            # url = sub.data.data_file.url
            url = SubmissionDetailSerializer(sub.data, context=self.get_serializer_context()).data['data_file']
            # url = SubmissionFilesSerializer(sub, context=self.get_serializer_context()).data['data_file']
            files.append({"name": short_name, "url": url})

        return Response(files)

        for sub in submissions:
            if sub.status not in [Submission.FINISHED]:  # Submission.FAILED, Submission.CANCELLED
                continue
            file_path = sub.data.data_file.name.split('/')[-1]
            complete_name = f"res_{sub.id}_{sub.owner}_PhaseId{sub.phase.id}_{sub.data.created_when.strftime('%Y-%m-%d:%M-%S')}_{file_path}"
            result_url = SubmissionDetailSerializer(sub.data, context=self.get_serializer_context()).get_scoring_result(sub)
            # detailed results is already in the results zip file but For very large detailed results it could be helpfull to remove it
            # detailed_result_url = serializer.get_scoring_result(sub)
            files.append({"name": complete_name, "url": result_url})

        return Response(files)

Everything that comes after the first return Response(files) will never be executed. It feels like another version of the same code, or under-progress version or something.

We can simply remove these lines, but I feel like there are interesting things that we can merge with the part above, like comments, the use of the prefix res_ in filename to avoid conflict between results and submissions, etc.