Abbreviated arguments don't show up in source_to_settings_dict

[wgreenberg]

Although I haven't seen much use/discussion of get_source_to_settings_dict(), since it's public API we use it in Certbot. But we recently noticed (certbot/certbot#9793) that if an argument is abbreviated, its entry in the sources dict has None for the corresponding action.

We're able to kinda work around it for now, but I figure it might be nice to fix this at some point. Note that the Certbot version from this issue uses ConfigArgparse 1.7