Update ETCD version and clean up statefulset

[t-persson]

Applicable Issues

I found no issue on this, but related to #387

Description of the Change

Update the ETCD version to the latest available at the time of this PR (v3.5.19).
Updated how we start the container so that it works with the newer version, but also went through and applied a few changes as per this documentation: https://etcd.io/docs/v3.5/op-guide/kubernetes/

Alternate Designs

Nothing really

Possible Drawbacks

I don't know how this will deploy in clusters that are running the old v3.3.8 version.

Sign-off

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Signed-off-by: Tobias Persson [email protected]