Clean out `upload_or_check_non_existence.py` from feedstocks.
Clean out `upload_or_check_non_existence.py` from feedstocks.

conda-forge/conda-smithy,ocefpaf/conda-smithy,conda-forge/conda-smithy,ocefpaf/conda-smithy,shadowwalkersb/conda-smithy,shadowwalkersb/conda-smithy