MEV rewards sent to addresses configured on the CL + VC before key splitting, not as specified in Charon's lock file

[boulder225]

🎯 Problem to be solved

Reports from two clusters indicate that MEV rewards are being sent to addresses configured on the CL + VC, not as specified in Charon's lock file. Validator keys previously operated solo are now part of a split and are experiencing issues with MEV reward distribution. The core of the problem seems to be related to timestamp discrepancies between Charon's builder registration (set to the genesis timestamp) and the timestamp used during the solo operation of these validators.

Problem identified

The timestamps on the builder registration while as a solo were greater than the genesis timestamp used by charon create cluster --split-existing-keys and thus took precedence

🛠️ Proposed solution

• Investigate the timestamp configuration in both the Charon cluster lock and the solo operation setups to understand the cause of the discrepancy.
• Modify the code for --split-existing-keys to use the current timestamp for pre-generated builder registration instead of the genesis timestamp.
• Document in a 'migration of a solo validator' page, that they need to turn off their mev-boost before they split keys to not run into this problem.

Future work

• If we add charon support to talk to a relay directly, have charon poll the /relay/v1/data/validator_registration endpoint to confirm if the MEV reward distribution matches the lock file settings, and mark charon as unhealthy if not.