Refactor the metrics end-to-end tests so they can be run with our e2e
test framework. Runs fabio/prometheus and a collection of jobs that
will cause metrics to be measured. We then query Prometheus to ensure
we're publishing those allocation metrics and some metrics from the
clients as well.
Includes adding a placeholder for running the same tests on Windows.
* Adds a constraint to prevent tests from landing on Windows
* Improve Terraform output for mixed windows/linux clients
* Makes some Windows client config fixes from 0.10.2 testing
