env_aws: get ec2 cpu perf data from AWS API

Previously, Nomad was using a hand-made lookup table for looking
up EC2 CPU performance characteristics (core count + speed = ticks).

This data was incomplete and incorrect depending on region. The AWS
API has the correct data but requires API keys to use (i.e. should not
be queried directly from Nomad).

This change introduces a lookup table generated by a small command line
tool in Nomad's tools module which uses the Amazon AWS API.

Running the tool requires AWS_* environment variables set.
  $ # in nomad/tools/cpuinfo
  $ go run .

Going forward, Nomad can incorporate regeneration of the lookup table
somewhere in the CI pipeline so that we remain up-to-date on the latest
offerings from EC2.

Fixes hashicorp#7830

CHANGELOG.md

@@ -8,6 +8,7 @@ IMPROVEMENTS:
  * client: Added support for Azure fingerprinting. [[GH-8979](https://github.com/hashicorp/nomad/issues/8979)]
  * client: Added support for fingerprinting the client node's Consul segment. [[GH-7214](https://github.com/hashicorp/nomad/issues/7214)]
  * client: Updated consul-template to v0.25.0 - config function_blacklist deprecated and replaced with function_denylist [[GH-8988](https://github.com/hashicorp/nomad/pull/8988)]
+ * client: Use ec2 CPU perf data from AWS API [[GH-7830](https://github.com/hashicorp/nomad/issues/7830)]
  * consul: Support Consul namespace (Consul Enterprise) in client configuration. [[GH-8849](https://github.com/hashicorp/nomad/pull/8849)]
  * csi: Relaxed validation requirements when checking volume capabilities with controller plugins, to accommodate existing plugin behaviors. [[GH-9049](https://github.com/hashicorp/nomad/issues/9049)]
  * driver/docker: Upgrade pause container and detect architecture [[GH-8957](https://github.com/hashicorp/nomad/pull/8957)]