[CI] SmokeTestMonitoringWithSecurityIT fails due to leaked thread

[dnhatn]

SmokeTestMonitoringWithSecurityIT failed due to leaked threads.

2> SEVERE: 1 thread leaked from SUITE scope at org.elasticsearch.smoketest.SmokeTestMonitoringWithSecurityIT: 
2>    1) Thread[id=18, name=threadDeathWatcher-2-1, state=TIMED_WAITING, group=TGRP-SmokeTestMonitoringWithSecurityIT]
2>         at java.lang.Thread.sleep(Native Method)
2>         at io.netty.util.ThreadDeathWatcher$Watcher.run(ThreadDeathWatcher.java:152)
2>         at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
2>         at java.lang.Thread.run(Thread.java:748)

• Instance: https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+master+multijob-windows-compatibility/1627/console

• Log: testHTTPExporterWithSSL.txt

[elasticmachine]

Pinging @elastic/es-security

[jasontedor]

This thread: threadDeathWatcher-2-1 is a Netty thread. I think this should be recategorized as :Core/Network issue.

[elasticmachine]

Pinging @elastic/es-core-infra