fix: changed list consumer groups fetching way from all to valid (#374)

src/main/java/kafdrop/service/KafkaHighLevelAdminClient.java

@@ -72,7 +72,7 @@ ClusterDescription describeCluster() {
   Set<String> listConsumerGroups() {
     final Collection<ConsumerGroupListing> groupListing;
     try {
-      groupListing = adminClient.listConsumerGroups().all().get();
+      groupListing = adminClient.listConsumerGroups().valid().get();
     } catch (InterruptedException | ExecutionException e) {
       throw new KafkaAdminClientException(e);
     }