Gloas sync notifier logs

[eserilev]

Description

Apr 06 01:23:06.001 INFO  Synced                                        peers: "2", exec_hash: "n/a", 
finalized_root: 0x6de6f3b119776e439e2f73f98cce6cdb4deba43338e580777c90488d970cd0e8, 
finalized_epoch: 1314, epoch: 1316, 
block: "0xde30df305abd0c87e99f1afa8767dbf2183dc67adc06f7af6f76fc23de484900", slot: 42115

our sync notifier shows exec_hash: "n/a" for Gloas. I think we should instead display Pending, Empty or Full depending on what beacon_chain.canonical_head.cached_head().head_payload_status() returns

We dont actually have the execution hash available in fork choice to display. I think thats okay. Maybe for post gloas the log field should be "payload_envelope_status" and it should display one one of the three payload status variants?

[luanxu-dev]

One lightweight improvement path here may be to make the notifier output more explicit about payload state instead of overloading exec_hash with n/a.

A practical validation flow could be:

1. Log the raw head_payload_status() variant alongside the current notifier output.
2. Compare notifier output across Pending / Empty / Full cases on the same devnet to confirm operators can distinguish state transitions quickly.
3. Keep the displayed field name aligned with what is actually known at fork-choice time, so the log does not imply an execution hash is available when it is not.
4. Add a small regression check for notifier output formatting so future changes do not collapse these states back into a generic n/a.