fix: flakey test testGetTopology_returnCachedTopology (#164)

`testGetTopology_returnCachedTopology` is flaky because when it calls `getTopology` `refreshNeeded(topology)` will always true. This method always return true because it checks if the elapsed time has exceeded `refreshRateInMilliseconds`, which is initialized to 0, so the elapsed time will always be greater.

Author: karenc-bq

wrapper/src/main/java/software/amazon/jdbc/hostlistprovider/AuroraHostListProvider.java

@@ -97,7 +97,10 @@ public class AuroraHostListProvider implements HostListProvider, DynamicHostList
   private RdsUrlType rdsUrlType;
   private final RdsUtils rdsHelper;
 
-  private int refreshRateInMilliseconds;
+  private int refreshRateInMilliseconds = Integer.parseInt(
+      CLUSTER_TOPOLOGY_REFRESH_RATE_MS.defaultValue != null
+          ? CLUSTER_TOPOLOGY_REFRESH_RATE_MS.defaultValue
+          : "30000");
   private List<HostSpec> hostList = new ArrayList<>();
   private List<HostSpec> lastReturnedHostList;
   private List<HostSpec> initialHostList = new ArrayList<>();