Delete empty distributions from the public nuxeo-explorer instance

The [platform explorer](https://explorer.nuxeo.com/nuxeo/site/distribution/) was importing and emptying distributions content from 2021.42 to 2021.46 included.

This results in empty distribs that would better be absent.

We could also think of uploading the missing distribs. That would mean uploading 2021.27 up till now.

A simple loop curling and waiting script could do that. However, the curl will only assert the upload, not the result of the import.

pseudo like this (if we can provide the distribs to import):

set -ex

for range 2021.42..2021.46; do
 curl delete the distrib
done;

for range 2021.27..2021.46; do
  curl import the distrib
  wait 10 minutes to be sure everything is finished
done;