[CI] IndexStatsIT testThrottleStats failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic-platform-support #8112 / almalinux-8-aarch64_checkpart1_platform-support-arm
• elasticsearch-periodic-platform-support #8112 / ubuntu-2404-aarch64_checkpart1_platform-support-arm
• elasticsearch-periodic-platform-support #8112 / ubuntu-2404_platform-support-unix
• elasticsearch-pull-request #71217 / part-1
• elasticsearch-periodic-platform-support #8106 / amazonlinux-2023_platform-support-aws

Reproduction Line:

./gradlew ":server:internalClusterTest" --tests "org.elasticsearch.indices.stats.IndexStatsIT.testThrottleStats" -Dtests.seed=AFB308EF37A80705 -Dtests.locale=en-MV -Dtests.timezone=Pacific/Ponape -Druntime.java=24

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: null

Issue Reasons:

• [main] 3 consecutive failures in test testThrottleStats
• [main] 5 failures in test testThrottleStats (3.2% fail rate in 157 executions)
• [main] 2 failures in pipeline elasticsearch-periodic-platform-support (50.0% fail rate in 4 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 testThrottleStats (1.9% fail rate in 155 executions)
• [main] 2 failures in pipeline elasticsearch-periodic-platform-support (50.0% fail rate in 4 executions)

Build Scans:

• elasticsearch-periodic-platform-support #8112 / ubuntu-2404_platform-support-unix
• elasticsearch-pull-request #71217 / part-1
• elasticsearch-periodic-platform-support #8106 / amazonlinux-2023_platform-support-aws

[arteam]

Seems to be caused by #127173

[arteam]

The test is failing on Engine.PauseLock#throttle

at __randomizedtesting.SeedInfo.seed([C5CC926EDF15D7F6]:0)	
	at org.elasticsearch.index.engine.Engine$PauseLock.throttle(Engine.java:615)	
	at org.elasticsearch.index.engine.Engine$IndexThrottle.activate(Engine.java:475)	
	at org.elasticsearch.index.engine.InternalEngine.activateThrottling(InternalEngine.java:2829)	
	at org.elasticsearch.index.engine.InternalEngine$EngineThreadPoolMergeScheduler.enableIndexingThrottling(InternalEngine.java:2923)	
	at org.elasticsearch.index.engine.ThreadPoolMergeScheduler.checkMergeTaskThrottling(ThreadPoolMergeScheduler.java:206)	
	at org.elasticsearch.index.engine.ThreadPoolMergeScheduler.submitNewMergeTask(ThreadPoolMergeScheduler.java:173)	
	at org.elasticsearch.index.engine.ThreadPoolMergeScheduler.merge(ThreadPoolMergeScheduler.java:128)	
	at org.elasticsearch.index.engine.ThreadPoolMergeScheduler$MergeTask.run(ThreadPoolMergeScheduler.java:415)	
	at org.elasticsearch.index.engine.ThreadPoolMergeExecutorService.runMergeTask(ThreadPoolMergeExecutorService.java:209)	
	at org.elasticsearch.index.engine.ThreadPoolMergeExecutorService.lambda$enqueueMergeTaskExecution$4(ThreadPoolMergeExecutorService.java:181)	
	at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:977)	
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1095)	
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:619)	
	at java.lang.Thread.run(Thread.java:1447)