Fix failing docker packaging tests due to too long commandline

Use jps for now to avoid issues with too long commandline when relying on plain ps ax and terminal specific COLUMN restrictions

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=3000 ps ax'").stdout();
+                psOutput = dockerShell.run("bash -c '/usr/share/elasticsearch/jdk/bin/jps -mlV'").stdout();
 
                 if (psOutput.contains("org.elasticsearch.bootstrap.Elasticsearch")) {
                     isElasticsearchRunning = true;