Add metrics for EE PayloadStatus returns (#3486)

## Issue Addressed

NA

## Proposed Changes

Adds some metrics so we can track payload status responses from the EE. I think this will be useful for troubleshooting and alerting.

I also bumped the `BecaonChain::per_slot_task` to `debug` since it doesn't seem too noisy and would have helped us with some things we were debugging in the past.

## Additional Info

NA

Cargo.lock

@@ -2083,6 +2083,7 @@ dependencies = [
  "slot_clock",
  "ssz-rs",
  "state_processing",
+ "strum",
  "task_executor",
  "tempfile",
  "tokio",