Improve error message when resource leaks are detected in test clusters (#109996)

We throw an error when we detect resource leaks in cluster logs but we
don't provide any indication of which cluster, or which log. This change
logs the path to the log file in question so you can investigate.

build-tools/src/main/java/org/elasticsearch/gradle/testclusters/ElasticsearchNode.java

@@ -1139,7 +1139,7 @@ public class ElasticsearchNode implements TestClusterConfiguration {
             }
         }
         if (foundLeaks) {
-            throw new TestClustersException("Found resource leaks in node logs.");
+            throw new TestClustersException("Found resource leaks in node log: " + from);
         }
     }