Update Geth dashboard with latest version

[remyroy]

Current Geth dashboard in constants.py needs to be updated with the latest version available on https://gist.github.com/karalabe/1e26f9ea5c842fb118584edadc454e18

[remyroy]

I'm working on a updated dashboard for Prometheus and Geth on https://github.com/remyroy/ethstaker/blob/main/dashboards/geth-grafana.json . That should eventually be even better than what the go-ethereum team is providing for this setup.

[remyroy]

I've been working on an updated version on https://github.com/remyroy/ethstaker/blob/main/dashboards/geth-grafana.json . That should be the most up-to-date . Work still need to be done there to fix some issues.