consensus: rm Receipts root_slow unused method (#1567)

* consensus: add unit tests for receipts root_slow and refac

* clippy

* rm root_slow fn

* clippy

crates/consensus/src/receipt/receipts.rs

@@ -1,6 +1,6 @@
 use crate::receipt::{Eip658Value, TxReceipt};
 use alloc::{vec, vec::Vec};
-use alloy_primitives::{Bloom, Log, B256};
+use alloy_primitives::{Bloom, Log};
 use alloy_rlp::{length_of_length, BufMut, Decodable, Encodable};
 use core::{borrow::Borrow, fmt};
 use derive_more::{DerefMut, From, IntoIterator};
@@ -126,12 +126,6 @@ impl<T> Receipts<T> {
     pub fn push(&mut self, receipts: Vec<T>) {
         self.receipt_vec.push(receipts);
     }
-
-    /// Retrieves all recorded receipts from index and calculates the root using the given closure.
-    pub fn root_slow(&self, index: usize, f: impl FnOnce(&[&T]) -> B256) -> Option<B256> {
-        let receipts = self.receipt_vec.get(index)?.iter().collect::<Vec<_>>();
-        Some(f(receipts.as_slice()))
-    }
 }
 
 impl<T> From<Vec<T>> for Receipts<T> {
@@ -301,6 +295,8 @@ where
 
 #[cfg(test)]
 mod test {
+    use super::*;
+
     #[cfg(feature = "serde")]
     #[test]
     fn root_vs_status() {