Description

When moving between clients, it's nice to know that the old client will not return from the dead and start validating with keys that were just moved to a new client. To disable keys in Lighthouse currently requires the user either to move/delete them from disk manually (which causes a failure on startup) or edit the validator definitions file to contain enabled: false. I think we should provide a one-shot command like lighthouse account validator disable-all which sets the enabled: false flag for all validators.

This would be particularly useful if the validator client is configured to run on startup, or in some other auto-restart configuration, which was the cause of this user's slashing (on a testnet): https://www.reddit.com/r/ethstaker/comments/mzgubm/why_you_should_switch_to_lighthouse/gw17n8y