I see two ways:
install the addon but do not restart. in the same session go to the addon folder inspect the code and move the addon folder or delete it. I haven’t looked at aqt/addon.py from the anki source but I would guess that the old behavior “running addon code requires a restart” hasn’t changed. In the past Damien considered this also as a feature and not just a bug, see e.g. here.
addons can also be downloaded from outside of anki. the adress for my addon should be ‘https://ankiweb.net/shared/download/1326170847?v=2.1&p=66’ . use your browsers or maybe a tool like wget.