fix: (mod-service)Use concurrent read cache (#10965)

Signed-off-by: Michael Tinker <[email protected]>
Co-authored-by: Michael Tinker <[email protected]>

hedera-node/hedera-app-spi/src/main/java/com/hedera/node/app/spi/state/ReadableKVStateBase.java

@@ -38,7 +38,7 @@ public abstract class ReadableKVStateBase<K, V> implements ReadableKVState<K, V>
      * changed before we got to handle transaction. If the value is "null", this means it was NOT
      * FOUND when we looked it up.
      */
-    private final Map<K, V> readCache = new HashMap<>();
+    private final Map<K, V> readCache = Collections.synchronizedMap(new HashMap<>());
 
     private final Set<K> unmodifiableReadKeys = Collections.unmodifiableSet(readCache.keySet());