Resolve "Cleanup in the welcome controller"

What does this MR do and why?

Remove the line that return users_almost_there_path. It's discovered during the discussion here: !107302 (comment 1283442858) that while email_confirmation_setting is hard, it's not possible for an unconfirmed user to be redirected back to users_almost_there_path, the user will be redirected to login always.

This is also reflected in the spec here: https://gitlab.com/gitlab-org/gitlab/-/blob/master/spec/controllers/registrations/welcome_controller_spec.rb#L91

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Related to #391998 (closed)