Remove state lru cache (#8724)

N/A


  In https://github.com/sigp/lighthouse/pull/4801 , we added a state lru cache to avoid having too many states in memory which was a concern with 200mb+ states pre tree-states.
With https://github.com/sigp/lighthouse/pull/5891 , we made the overflow cache a simpler in memory lru cache that can only hold 32 pending states at the most and doesn't flush anything to disk. As noted in #5891, we can always fetch older blocks which never became available over rpc if they become available later.

Since we merged tree states, I don't think the state lru cache is relevant anymore. Instead of having the `DietAvailabilityPendingExecutedBlock` that stores only the state root, we can just store the full state in the `AvailabilityPendingExecutedBlock`.
Given entries in the cache can span max 1 epoch (cache size is 32), the underlying `BeaconState` objects in the cache share most of their memory. The state_lru_cache is one level of indirection that doesn't give us any benefit.
Please check me on this cc @dapplion


Co-Authored-By: Pawan Dhananjay <pawandhananjay@gmail.com>

beacon_node/beacon_chain/src/data_availability_checker.rs

@@ -5,9 +5,7 @@ use crate::block_verification_types::{AvailabilityPendingExecutedBlock, Availabl
 use crate::data_availability_checker::overflow_lru_cache::{
     DataAvailabilityCheckerInner, ReconstructColumnsDecision,
 };
-use crate::{
-    BeaconChain, BeaconChainTypes, BeaconStore, BlockProcessStatus, CustodyContext, metrics,
-};
+use crate::{BeaconChain, BeaconChainTypes, BlockProcessStatus, CustodyContext, metrics};
 use educe::Educe;
 use kzg::Kzg;
 use slot_clock::SlotClock;
@@ -27,7 +25,6 @@ use types::{
 
 mod error;
 mod overflow_lru_cache;
-mod state_lru_cache;
 
 use crate::data_availability_checker::error::Error;
 use crate::data_column_verification::{
@@ -53,7 +50,6 @@ use types::new_non_zero_usize;
 /// `PendingComponents` are now never removed from the cache manually are only removed via LRU
 /// eviction to prevent race conditions (#7961), so we expect this cache to be full all the time.
 const OVERFLOW_LRU_CAPACITY_NON_ZERO: NonZeroUsize = new_non_zero_usize(32);
-const STATE_LRU_CAPACITY_NON_ZERO: NonZeroUsize = new_non_zero_usize(32);
 
 /// Cache to hold fully valid data that can't be imported to fork-choice yet. After Dencun hard-fork
 /// blocks have a sidecar of data that is received separately from the network. We call the concept
@@ -122,13 +118,11 @@ impl<T: BeaconChainTypes> DataAvailabilityChecker<T> {
         complete_blob_backfill: bool,
         slot_clock: T::SlotClock,
         kzg: Arc<Kzg>,
-        store: BeaconStore<T>,
         custody_context: Arc<CustodyContext<T::EthSpec>>,
         spec: Arc<ChainSpec>,
     ) -> Result<Self, AvailabilityCheckError> {
         let inner = DataAvailabilityCheckerInner::new(
             OVERFLOW_LRU_CAPACITY_NON_ZERO,
-            store,
             custody_context.clone(),
             spec.clone(),
         )?;
@@ -469,7 +463,6 @@ impl<T: BeaconChainTypes> DataAvailabilityChecker<T> {
     /// Collects metrics from the data availability checker.
     pub fn metrics(&self) -> DataAvailabilityCheckerMetrics {
         DataAvailabilityCheckerMetrics {
-            state_cache_size: self.availability_cache.state_cache_size(),
             block_cache_size: self.availability_cache.block_cache_size(),
         }
     }
@@ -565,7 +558,6 @@ impl<T: BeaconChainTypes> DataAvailabilityChecker<T> {
 
 /// Helper struct to group data availability checker metrics.
 pub struct DataAvailabilityCheckerMetrics {
-    pub state_cache_size: usize,
     pub block_cache_size: usize,
 }
 
@@ -912,7 +904,6 @@ mod test {
     use std::collections::HashSet;
     use std::sync::Arc;
     use std::time::Duration;
-    use store::HotColdDB;
     use types::data::DataColumn;
     use types::{
         ChainSpec, ColumnIndex, DataColumnSidecarFulu, EthSpec, ForkName, MainnetEthSpec, Slot,
@@ -1253,7 +1244,6 @@ mod test {
             spec.get_slot_duration(),
         );
         let kzg = get_kzg(&spec);
-        let store = Arc::new(HotColdDB::open_ephemeral(<_>::default(), spec.clone()).unwrap());
         let ordered_custody_column_indices = generate_data_column_indices_rand_order::<E>();
         let custody_context = Arc::new(CustodyContext::new(
             NodeCustodyType::Fullnode,
@@ -1265,7 +1255,6 @@ mod test {
             complete_blob_backfill,
             slot_clock,
             kzg,
-            store,
             custody_context,
             spec,
         )