Deneb PR feedback updates (#4716)

* move length update outside of if let in LRU cache

* add comment and use hex for G1_POINT_AT_INFINITY

* remove some misleading comments from `ssz_snappy`

* make sure we can't overflow on blobs by range requests with large counts

* downgrade gossip verification internal availability check error

* change blob rpc responses from BlockingFnWithManualSendOnIdle to BlockingFn

* remove unnecessary collect in blobs by range response

* add a comment to blobs by range response start slot logic

* typo persist_data_availabilty_checker -> persist_data_availability_checker

* unify cheap_state_advance_to_obtain_committees

crypto/kzg/src/kzg_proof.rs

@@ -24,9 +24,10 @@ impl From<KzgProof> for c_kzg_min::Bytes48 {
 }
 
 impl KzgProof {
+    /// Creates a valid proof using `G1_POINT_AT_INFINITY`.
     pub fn empty() -> Self {
         let mut bytes = [0; BYTES_PER_PROOF];
-        bytes[0] = 192;
+        bytes[0] = 0xc0;
         Self(bytes)
     }
 }