[Test] Rework detecting elasticsearch process in docker tests

This tweaks detecting the elasticsearch process id by using jps instead of ps which has been problematic in the past exceeding available COLUMN sizes due to es commandline invocation getting longer and longer

Author: breskeby

qa/packaging/src/test/java/org/elasticsearch/packaging/util/docker/Docker.java

@@ -187,7 +187,7 @@ public static void waitForElasticsearchToStart() {
                 Thread.sleep(STARTUP_SLEEP_INTERVAL_MILLISECONDS);
 
                 // Set COLUMNS so that `ps` doesn't truncate its output
-                psOutput = dockerShell.run("bash -c 'COLUMNS=4000 ps ax'").stdout();
+                psOutput = dockerShell.run("bash -c 'COLUMNS=1000 jdk/bin/jps -ml'").stdout();
 
                 if (psOutput.contains("org.elasticsearch.bootstrap.Elasticsearch")) {
                     isElasticsearchRunning = true;