Remove miscellaneous VaultPress references/code

To be clear, let's not tackle all of these in a single PR. :)

- [ ] Navigation - Looks like VaultPress being activated is a conditional on [line 186](https://github.com/Automattic/jetpack/blob/master/_inc/client/components/navigation-settings/index.jsx#L186) in `_inc/client/components/navigation-settings/index.jsx`
- [ ] Settings Card - Looks like data is pulled in inside `_inc/client/components/settings-card/index.jsx` for VaultPress on lines 34, 56, and 299
- [ ] Pro Status - Reference a bunch here `_inc/client/pro-status/index.jsx` but I'm not sure what for
- [ ] Rest API - `_inc/client/rest-api/index.js` line 64
- [ ] State - `_inc/client/state/action-types.js` lines 53-55
- [ ] Endpoints - `_inc/lib/core-api/class.jetpack-core-api-module-endpoints.php` We need to remove the VaultPress messaging (do a quick search for VaultPress)
- [ ] JP admin - Just remove the reference in `class.jetpack-admin.php` on line 181
- [ ] JP CLI - `class.jetpack-cli.php` lines 334-348
- [ ] JP module list - `class.jetpack-modules-list-table.php` line 99
- [ ] Module info - `modules/module-info.php` Do these do anything?
- [ ] `class.jetpack.php` not sure what the references here do
- [x] `docs/rest-api.md` Just remove the reference
- [ ] `tests/php/sync/server/class.jetpack-sync-test-object-factory.php` No idea what this is
- [ ] Old styles - `scss/templates/_settings.scss` Remove styles targeting a `.vaultpress` selector

Start by searching the listed JavaScript, PHP, SCSS, and test paths for VaultPress references, especially the client components, core API endpoints, CLI, module files, and old styles. Handle one checklist area per change, and consider the area done when its obsolete references are removed without affecting the surrounding behavior or relevant tests.

Written by the indexing model from the issue text.