Increase the shortened timeout after the first loop so that metrics
that take longer to come in aren't failing the test unnecessarily.
Move the check for empty alloc metrics into the loop so that if the
first values we get are empty we don't fail the test too early.
Adds Windows targets to the client/allocs metrics tests. Removes the
`allocstats` test, which covers less than these tests and is now
redundant.
Adds a firewall rule to our Windows instances so that the prometheus
server can scrape the Nomad HTTP API for metrics.
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.
Seth Hoenig