Remove unused config values

We have a good number of config values that are remnants of old features. We should remove these when possible, and send out the new config to be replaced everywhere (including botconfig.example.js in this repo)

The only concrete target is `botconfig.example.js`; open it first and enumerate the config keys that should be removed. Then search the TypeScript codebase for each key’s usages and update only the files that still rely on removed values so configuration references are consistent. No specific tests are named, so run the repository’s normal checks afterward; this issue is done when stale keys are removed from `botconfig.example.js` and no remaining references are left.

索引モデルが issue の本文から書いたものです。