Discussion: not return headers to CL client if >3 sec into slot?

Proposers with slow network connection might call getPayload too late (getPayload requests arriving at the relay >4s into the slot will be rejected).

If there's a slow connection, getHeader will probably also be slow.

Should mev-boost not return headers to CL client if >3 sec into the slot, as the getPayload request would likely end up too late at the relay?

Could also make this opt-in or opt-out 🤔

cc/ @ralexstokes @jtraglia @terencechain @michaelneuder

See instances of this happening to users, when getHeader response was received at 3 seconds into the slot:

- https://github.com/flashbots/mev-boost/issues/517
- https://github.com/flashbots/mev-boost/issues/516