Fix logging of cluster state update descriptions

In elastic#28941 we changed the computation of cluster state task descriptions but
this introduced a bug in which we only log the empty descriptions (rather than
the non-empty ones). This PR fixes that.

server/src/main/java/org/elasticsearch/cluster/ClusterStateTaskExecutor.java

@@ -58,7 +58,7 @@ default void clusterStatePublished(ClusterChangedEvent clusterChangedEvent) {
      * This allows groupd task description but the submitting source.
      */
     default String describeTasks(List<T> tasks) {
-        return String.join(", ", tasks.stream().map(t -> (CharSequence)t.toString()).filter(t -> t.length() == 0)::iterator);
+        return String.join(", ", tasks.stream().map(t -> (CharSequence)t.toString()).filter(t -> t.length() > 0)::iterator);
     }
 
     /**