[CI] ManyShardsIT testRejection failing

Build Scans:

Reproduction Line:

./gradlew ':x-pack:plugin:esql:internalClusterTest' --tests "org.elasticsearch.xpack.esql.action.ManyShardsIT.testConcurrentQueries" -Dtests.seed=80F09AF3784880C3 -Dbuild.snapshot=false -Dtests.jvm.argline="-Dbuild.snapshot=false" -Dlicense.key=x-pack/license-tools/src/test/resources/public.key -Dtests.locale=az -Dtests.timezone=Pacific/Guadalcanal -Druntime.java=22

Applicable branches: 8.15

Reproduces locally?: N/A

Failure History: See dashboard&_a=(controlGroupState:(initialChildControlState:('0c0c9cb8-ccd2-45c6-9b13-96bac4abc542':(dataViewId:fbbdc689-be23-4b3d-8057-aa402e9ed0c5,fieldName:task.keyword,order:0,selectedOptions:!(),title:'GradleTask',type:optionsListControl),'4e6ad9d6-6fdc-4fcc-bf1a-aa6ca79e0850':(dataViewId:fbbdc689-be23-4b3d-8057-aa402e9ed0c5,fieldName:className.keyword,order:1,selectedOptions:!(org.elasticsearch.xpack.esql.action.ManyShardsIT),title:'Suite',type:optionsListControl),'144933da-5c1b-4257-a969-7f43455a7901':(dataViewId:fbbdc689-be23-4b3d-8057-aa402e9ed0c5,fieldName:name.keyword,order:2,selectedOptions:!(testRejection),title:'Test',type:optionsListControl)))))

Failure Message:

java.lang.AssertionError: Leftover exchanges ExchangeService{sinks=[ByoKMk2eTNimB2VubcnUAQ:660]} on node node_s1

Issue Reasons:

[8.15] 2 consecutive failures in step rhel-7_platform-support-unix
[8.15] 13 failures in test testRejection (2.1% fail rate in 611 executions)
[8.15] 4 failures in step rhel-7_platform-support-unix (21.1% fail rate in 19 executions)
[8.15] 2 failures in pipeline elasticsearch-periodic (10.0% fail rate in 20 executions)
[8.15] 8 failures in pipeline elasticsearch-periodic-platform-support (40.0% fail rate in 20 executions)

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

elastic / elasticsearch

[CI] ManyShardsIT testRejection failing #117418