Delete duplicated serde code (#6027)

* Delete duplicated serde code

consensus/types/src/indexed_attestation.rs

@@ -53,10 +53,10 @@ use tree_hash_derive::TreeHash;
 pub struct IndexedAttestation<E: EthSpec> {
     /// Lists validator registry indices, not committee indices.
     #[superstruct(only(Base), partial_getter(rename = "attesting_indices_base"))]
-    #[serde(with = "quoted_variable_list_u64")]
+    #[serde(with = "ssz_types::serde_utils::quoted_u64_var_list")]
     pub attesting_indices: VariableList<u64, E::MaxValidatorsPerCommittee>,
     #[superstruct(only(Electra), partial_getter(rename = "attesting_indices_electra"))]
-    #[serde(with = "quoted_variable_list_u64")]
+    #[serde(with = "ssz_types::serde_utils::quoted_u64_var_list")]
     pub attesting_indices: VariableList<u64, E::MaxValidatorsPerSlot>,
     pub data: AttestationData,
     pub signature: AggregateSignature,
@@ -203,43 +203,6 @@ impl<E: EthSpec> Hash for IndexedAttestation<E> {
     }
 }
 
-/// Serialize a variable list of `u64` such that each int is quoted. Deserialize a variable
-/// list supporting both quoted and un-quoted ints.
-///
-/// E.g.,`["0", "1", "2"]`
-mod quoted_variable_list_u64 {
-    use super::*;
-    use crate::Unsigned;
-    use serde::ser::SerializeSeq;
-    use serde::{Deserializer, Serializer};
-    use serde_utils::quoted_u64_vec::{QuotedIntVecVisitor, QuotedIntWrapper};
-
-    pub fn serialize<S, T>(value: &VariableList<u64, T>, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-        T: Unsigned,
-    {
-        let mut seq = serializer.serialize_seq(Some(value.len()))?;
-        for &int in value.iter() {
-            seq.serialize_element(&QuotedIntWrapper { int })?;
-        }
-        seq.end()
-    }
-
-    pub fn deserialize<'de, D, T>(deserializer: D) -> Result<VariableList<u64, T>, D::Error>
-    where
-        D: Deserializer<'de>,
-        T: Unsigned,
-    {
-        deserializer
-            .deserialize_any(QuotedIntVecVisitor)
-            .and_then(|vec| {
-                VariableList::new(vec)
-                    .map_err(|e| serde::de::Error::custom(format!("invalid length: {:?}", e)))
-            })
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;