Ensure official content lists are correct

[TylerBre]

These lists are compiled from the seed helper and are probably about 90% accurate. They are used to tell which content should be added to the database when running npm run db:seed.

They probably contain a bit of third-part content that needs to be removed, as well as missing some official content.

Car list:
https://github.com/TylerBre/acserver_manager/blob/master/seed/content/official_car_list.json

Car liveries list:
https://github.com/TylerBre/acserver_manager/blob/master/seed/content/official_car_liveries_list.json

Track list:
https://github.com/TylerBre/acserver_manager/blob/master/seed/content/official_track_list.json

[TylerBre]

#2 might be affected by inconsistencies in these lists