The tool (Phetools' pdf_to_djvu_cgi.py) that IA Upload uses to convert IA PDFs into DjVu is no longer operational, so we should remove the option from IA Upload.
There is no great advantage to be had from creating DjVus from these PDFs; the original PDFs can be uploaded directly.
The error that's currently occurring a few times a week looks like:
[2024-04-27T08:12:01.987032+00:00] LOG.INFO: Creating DjVu for in.ernet.dli.2015.285133 from Pdf [] [] [2024-04-27T08:12:01.989211+00:00] LOG.INFO: Requesting start of conversion of in.ernet.dli.2015.285133 [] [] [2024-04-27T08:12:02.153205+00:00] LOG.CRITICAL: Server error: `GET http://tools.wmflabs.org/phetools/pdf_to_djvu_cgi.py?cmd=convert&ia_id=in.ernet.dli.2015.285133` resulted in a `503 SERVICE UNAVAILABLE` response: <!DOCTYPE HTML> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <m (truncated...) [] [] In RequestException.php line 113: Server error: `GET http://tools.wmflabs.org/phetools/pdf_to_djvu_cgi.py?cmd =convert&ia_id=in.ernet.dli.2015.285133` resulted in a `503 SERVICE UNAVAIL ABLE` response: <!DOCTYPE HTML> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <m (truncated...)