Request for arm64 machines to run GH action runners for etcd-io

[dims]

The etcd team had marked arm64 in their Tier 1 here before, but then downgraded it to Tier 3 as they lost access to the arm64 infrastructure https://etcd.io/docs/v3.5/op-guide/supported-platform/

Please see for context:

• https://github.com/etcd-io/etcd/issues/14748
• https://groups.google.com/g/etcd-dev/c/3s-GT1t8kBc/m/s3k7UoLoBQAJ

Could we please have a couple of arm64 boxes to run our CI jobs?

[dims]

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