Two pass refactoring continued.
Remove testing of whether we estimate that it will be possible to code an arf at a lower Q than the ambient Q. This adds quite a bit of extra code and complexity for marginal gain. Factored out some code relating to ARNR selection to a separate function as this is likely to be changed / simplified soon. Change-Id: Ia1cf060405637ef5bbf7018355437be21d12375f