[CI] ThreadPoolMergeExecutorServiceDiskSpaceTests testMergeTasksAreUnblockedWhenMoreDiskSpaceBecomesAvailable failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #9119 / openjdk17_checkpart1_java-matrix
• elasticsearch-pull-request #78797 / part-1
• elasticsearch-periodic-platform-support #9126 / almalinux-8_platform-support-unix
• elasticsearch-periodic-platform-support #9020 / rocky-9_platform-support-unix

Reproduction Line:

./gradlew ":server:test" --tests "org.elasticsearch.index.engine.ThreadPoolMergeExecutorServiceDiskSpaceTests.testMergeTasksAreUnblockedWhenMoreDiskSpaceBecomesAvailable" -Dtests.seed=906F473D65E74060 -Dtests.locale=es-EA -Dtests.timezone=Europe/Prague -Druntime.java=17

Applicable branches:
8.19

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

com.carrotsearch.randomizedtesting.UncaughtExceptionError: Captured an uncaught exception in thread: Thread[id=470, name=elasticsearch[test][merge][T#2], state=RUNNABLE, group=TGRP-ThreadPoolMergeExecutorServiceDiskSpaceTests]

Issue Reasons:

• [8.19] 4 failures in test testMergeTasksAreUnblockedWhenMoreDiskSpaceBecomesAvailable (0.6% fail rate in 637 executions)
• [8.19] 2 failures in pipeline elasticsearch-periodic-platform-support (11.8% fail rate in 17 executions)

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

[elasticsearchmachine]

Pinging @elastic/es-distributed-indexing (Team:Distributed Indexing)

[elasticsearchmachine]

This has been muted on branch main

Mute Reasons:

• [main] 3 failures in test testMergeTasksAreUnblockedWhenMoreDiskSpaceBecomesAvailable (0.6% fail rate in 522 executions)
• [main] 2 failures in step part-1 (1.1% fail rate in 183 executions)
• [main] 2 failures in pipeline elasticsearch-pull-request (1.1% fail rate in 182 executions)

Build Scans:

• elasticsearch-periodic-platform-support #8796 / debian-12_platform-support-unix
• elasticsearch-pull-request #75382 / part-1
• elasticsearch-pull-request #75276 / part-1