Change sbws scaling method to torflow

I tried to fix this as part of legacy/trac#28442 (moved), but I couldn't get it to work:

# TODO: change scaling_method to TORFLOW_SCALING before getting this
# in production

https://github.com/torproject/sbws/blob/821f86e8392bc05579f7785e6907be6cc3844fef/sbws/lib/v3bwfile.py#L484

Are there any other TODOs that should be fixed?