Fix rake when cucumber gem is not present

Ensure `rake` works without the cucumber gem.

## Verification Steps

- [ ] Run: `bundle install --without test`
- [ ] VERIFY: `rake -T` lists tasks.  No stacktraces.
- [ ] Run: `bundle config --delete without`
- [ ] Run: `bundle install`
- [ ] VERIFY: `rake -T` lists tasks.  No stacktraces.