Make get_all_server_info and get_scaling_group_servers use pure-http

The metrics.py code had to be updated to deal with this, and I refactored the effectiness a little bit into metrics.py, so that there's a new get_all_metrics_effects function extracted from get_all_metrics.

I've added unit tests for get_all_metrics_effects, and left the unit tests for get_all_metrics in place (and updated them to ensure that code is using pure-HTTP properly). The tests for that are pretty nasty, but hopefully they'll go away if more of metrics.py gets Effect-ified.


Yeah. Understandable piece of currently necessary distastefulness. With the test suite in its current state, we can't expect to get rid of all mocks in one go :) Thank you for compartmentalizing the ugly, though!