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/builder.rs

@@ -1049,7 +1049,6 @@ where
                     complete_blob_backfill,
                     slot_clock,
                     self.kzg.clone(),
-                    store,
                     Arc::new(custody_context),
                     self.spec,
                 )