[BUG] Sandbox flaky test failure for AnalyticsQueryTaskCleanupIT

Describe the bug

Test testQtfFetchCancelTearsDownAndCleansUp of AnalyticsQueryTaskCleanupIT suite fails intermittently with below error

AnalyticsQueryTaskCleanupIT > testQtfFetchCancelTearsDownAndCleansUp FAILED
    java.lang.AssertionError: injected failure on indices:data/read/analytics/fetch_by_row_ids must fail the QTF query, not return (response=org.opensearch.ppl.action.PPLResponse@6d6326e9)
        at __randomizedtesting.SeedInfo.seed([47CD2BA433B27B2A:CE953F2EA8F7C393]:0)
        at org.junit.Assert.fail(Assert.java:89)
        at org.junit.Assert.assertTrue(Assert.java:42)
        at org.junit.Assert.assertNotNull(Assert.java:713)
        at org.opensearch.analytics.cancellation.AnalyticsQueryTaskCleanupIT.assertQtfInjectedFailureSurfacesAndCleansUp(AnalyticsQueryTaskCleanupIT.java:611)
        at org.opensearch.analytics.cancellation.AnalyticsQueryTaskCleanupIT.testQtfFetchCancelTearsDownAndCleansUp(AnalyticsQueryTaskCleanupIT.java:580)
REPRODUCE WITH: ./gradlew ':sandbox:qa:analytics-engine-coordinator:internalClusterTest' --tests 'org.opensearch.analytics.cancellation.AnalyticsQueryTaskCleanupIT.testQtfFetchCancelTearsDownAndCleansUp' -Dtests.seed=47CD2BA433B27B2A -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=zh-Hans -Dtests.timezone=America/North_Dakota/Center -Druntime.java=25

Example CI run - https://github.com/opensearch-project/OpenSearch/actions/runs/31486689089/job/93763602514?pr=22415

Related component

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To Reproduce

./gradlew ':sandbox:qa:analytics-engine-coordinator:internalClusterTest' --tests 'org.opensearch.analytics.cancellation.AnalyticsQueryTaskCleanupIT.testQtfFetchCancelTearsDownAndCleansUp' -Dtests.seed=47CD2BA433B27B2A -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=zh-Hans -Dtests.timezone=America/North_Dakota/Center -Druntime.java=25

Expected behavior

Test should pass consistently.

Additional Details

N/A

Start with AnalyticsQueryTaskCleanupIT.testQtfFetchCancelTearsDownAndCleansUp and reproduce it using the provided Gradle command, seed, and runtime settings. Inspect the assertions around AnalyticsQueryTaskCleanupIT lines 580 and 611 and determine why the injected fetch_by_row_ids failure sometimes returns instead of failing the QTF query. Done means the test passes consistently and still verifies teardown and cleanup.