Factory-spec helper cleanup.

Moved `#setup_user_fields` method from `FeatureSpecHelperBase` to
`FeatureSpecLoginHelper` where it makes more sense (since the fields
are added to the current `RSpec::Core::ExampleGroup` instance anyway).

Also changed `UserData` factory to sequence email addresses, matching
user names.

RSpec: 420 examples, 0 failures
RuboCop: 116 files inspected, no offenses detected