Optimize stakes cache and rewards at epoch boundaries (backport #20432) (#20472)

* Optimize stakes cache and rewards at epoch boundaries (backport #20432)

* fix conflicts

local-cluster/src/validator_configs.rs

@@ -57,6 +57,7 @@ pub fn safe_clone_config(config: &ValidatorConfig) -> ValidatorConfig {
         poh_hashes_per_batch: config.poh_hashes_per_batch,
         no_wait_for_vote_to_start_leader: config.no_wait_for_vote_to_start_leader,
         accounts_shrink_ratio: config.accounts_shrink_ratio,
+        disable_epoch_boundary_optimization: config.disable_epoch_boundary_optimization,
     }
 }