Change date format in cluster_usage_metrics_ files (#340)

Author: kpiotrowski

dumper/app/src/main/java/com/google/edwmigration/dumper/application/dumper/connector/redshift/RedshiftRawLogsConnector.java

@@ -258,7 +258,7 @@ private void makeClusterMetricsTasks(
       ImmutableList<MetricConfig> metrics,
       List<? super Task<?>> out) {
     DateTimeFormatter dateFormat =
-        DateTimeFormatter.ofPattern("yyyy-MM-dd_HHmmss").withZone(ZoneOffset.UTC);
+        DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HHmmss'Z'").withZone(ZoneOffset.UTC);
 
     AbstractAwsApiTask.createCredentialsProvider(arguments)
         .ifPresent(