Fix test review issues

- Remove wrong latest_message assertions from payload attestation test
  (on_payload_attestation writes to PTC bitfields, not vote tracker)
- Fix corrupted comment: "votes.gloas_enabled() to the genesis block"
  → "votes to the genesis block"
- Fix http_api test fallback string: "n/a" → "irrelevant" to match
  production code
- Add issue link to #[ignore] test
- Add comment explaining head_payload_status as u8 cast

consensus/fork_choice/src/fork_choice.rs

@@ -1285,7 +1285,7 @@ where
         //  2. Ignore all attestations to the zero hash.
         //
         // (1) becomes weird once we hit finality and fork choice drops the genesis block. (2) is
-        // fine because votes.gloas_enabled() to the genesis block are not useful; all validators implicitly attest
+        // fine because votes to the genesis block are not useful; all validators implicitly attest
         // to genesis just by being present in the chain.
         if attestation.data().beacon_block_root == Hash256::zero() {
             return Ok(());

consensus/fork_choice/tests/tests.rs

@@ -172,7 +172,8 @@ impl ForkChoiceTest {
         self
     }
 
-    /// Inspect the queued payload attestations in fork choice.
+    // TODO(gloas): add inspect_queued_payload_attestations when payload
+    // attestation queueing tests are implemented.
     #[allow(dead_code)]
     pub fn inspect_queued_payload_attestations<F>(self, mut func: F) -> Self
     where
@@ -971,6 +972,8 @@ async fn invalid_attestation_future_block() {
 /// `validate_on_attestation`, which requires a block to exist at a GLOAS-enabled slot.
 /// Currently the mock execution layer cannot produce Gloas blocks (no
 /// `signed_execution_payload_bid` support).
+/// TODO(gloas): un-ignore once mock EL supports Gloas blocks.
+/// https://github.com/sigp/lighthouse/issues/9025
 #[ignore]
 #[tokio::test]
 async fn invalid_attestation_payload_during_same_slot() {
@@ -1045,14 +1048,6 @@ async fn payload_attestation_for_previous_slot_is_accepted_at_next_slot() {
         "payload attestation at slot S should be accepted at S+1, got: {:?}",
         result
     );
-
-    let latest_message = chain
-        .canonical_head
-        .fork_choice_read_lock()
-        .latest_message(0)
-        .expect("latest message should exist");
-    assert_eq!(latest_message.slot, current_slot);
-    assert!(latest_message.payload_present);
 }
 
 /// Gossip payload attestations must be for the current slot. A payload attestation for slot S