QoL: Silence startup Prometheus errors

[yorickdowne]

Is your feature request related to a problem? Please describe.

Getting the version is noisy. It's not a huge deal; it'd still be nice to just get the version string for ./ethd version

Describe the solution you'd like

Silence the Prometheus errors during startup. Here's an example --version call:

2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
2022/09/27 17:47:56 could not register prometheus collector
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