default some tests to write cache = true (#28917)

core/src/validator.rs

@@ -244,6 +244,7 @@ impl Default for ValidatorConfig {
 impl ValidatorConfig {
     pub fn default_for_test() -> Self {
         Self {
+            accounts_db_caching_enabled: true,
             enforce_ulimit_nofile: false,
             rpc_config: JsonRpcConfig::default_for_test(),
             ..Self::default()

local-cluster/tests/local_cluster.rs

@@ -2229,6 +2229,7 @@ fn test_hard_fork_with_gap_in_roots() {
 
     let validator_config = ValidatorConfig {
         snapshot_config: Some(LocalCluster::create_dummy_load_only_snapshot_config()),
+        accounts_db_caching_enabled: true,
         ..ValidatorConfig::default()
     };
     let mut config = ClusterConfig {