Add cluster name and ephemeral storage tags for cluster autoscaler

[tbarrella]

PR o'clock

Description

Adds tags to all node groups to address #297:

• "k8s.io/cluster-autoscaler/{cluster-name}" (recommended by documentation in case of multiple clusters)
• "k8s.io/cluster-autoscaler/node-template/resources/ephemeral-storage" to support scaling from 0. Note that the PR to support this in CA is merged into master, but I haven't seen it merged into a release yet

I wasn't sure if it was ok to put these tags in all node groups. Doing so seemed ok since "cluster-autoscaler/disabled" is put in non-CA groups. Could potentially only put these in groups with "autoscaling_enabled," although might need help figuring out how

Checklist

• terraform fmt and terraform validate both work from the root and examples/eks_test_fixture directories (look in CI for an example)
• Tests for the changes have been added and passing (for bug fixes/features)
• Test results are pasted in this PR (in lieu of CI)
• I've added my change to CHANGELOG.md
• Any breaking changes are highlighted above

[max-rocket-internet]

Awesome, thanks @tbarrella !

[github-actions]

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