[CI] SearchWithRejectionsIT testOpenContextsAfterRejections failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic-platform-support #9212 / rhel-8_platform-support-unix
• elasticsearch-periodic-platform-support #9198 / almalinux-8_platform-support-unix
• elasticsearch-periodic #9171 / encryption-at-rest

Reproduction Line:

./gradlew ":server:internalClusterTest" --tests "org.elasticsearch.search.SearchWithRejectionsIT.testOpenContextsAfterRejections" -Dtests.seed=C6CEF24E9DAB155A -Dtests.locale=uk -Dtests.timezone=America/Thunder_Bay -Druntime.java=24

Applicable branches:
9.1

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: 
Expected: <0L>
     but: was <1L>

Issue Reasons:

• [9.1] 3 failures in test testOpenContextsAfterRejections (2.8% fail rate in 106 executions)
• [9.1] 2 failures in pipeline elasticsearch-periodic-platform-support (40.0% fail rate in 5 executions)

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

[elasticsearchmachine]

This has been muted on branch main

Mute Reasons:

• [main] 3 failures in test testOpenContextsAfterRejections (0.4% fail rate in 731 executions)
• [main] 2 failures in step part1 (1.9% fail rate in 108 executions)
• [main] 2 failures in pipeline elasticsearch-intake (1.9% fail rate in 108 executions)

Build Scans:

• elasticsearch-intake #21394 / part1
• elasticsearch-pull-request #65761 / part-1
• elasticsearch-intake #21056 / part1

[elasticsearchmachine]

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

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)

[drempapis]

I was able to reproduce the error while executing the test annotated with @Repeat(iterations = 500, useConstantSeed = true), which failed only once. One contributing factor appears to be that the framework randomly initializes either a SearchService or a MockSearchService, and the failure observed in the CI logs corresponds to a run using MockSearchService.