[CI] RestCancellableNodeClientTests testConcurrentExecuteAndClose failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic-platform-support #8202 / ubuntu-2004-aarch64_checkpart1_platform-support-arm
• elasticsearch-periodic-platform-support #8094 / ubuntu-2004_platform-support-unix

Reproduction Line:

./gradlew ":server:test" --tests "org.elasticsearch.rest.action.RestCancellableNodeClientTests.testConcurrentExecuteAndClose" -Dtests.seed=C00B660EC9AB68A2 -Dtests.locale=kok-Deva -Dtests.timezone=Europe/Zagreb -Druntime.java=24

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: expected:<0> but was:<1>

Issue Reasons:

• [main] 2 failures in test testConcurrentExecuteAndClose (0.3% fail rate in 717 executions)
• [main] 2 failures in pipeline elasticsearch-periodic-platform-support (10.5% fail rate in 19 executions)

Note:
This issue was created using new test triage automation. Please report issues or feedback to es-delivery.

[elasticsearchmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[DaveCTurner]

Test introduced recently in #126686 and this seems to be a test bug. Still investigating.

[elasticsearchmachine]

Pinging @elastic/es-distributed-coordination (Team:Distributed Coordination)