Audit CircleCI & Keybase Env Vars

[cthulhuplus]

There has been drift between what is in Keybase and in CircleCI. There are also old and unused env vars in CircleCI and Keybase that are "muddying" up the list of env vars. I need to audit these to bring them back into alignment with each other and remove the clutter.

This task is done when...

• [ ] The list of env vars being used is consistent between CircleCI and Keybase
• [ ] Old and unused env vars are removed from CircleCI and Keybase
• [ ] Everything still works