[CI] RandomizedTimeSeriesIT testGroupBySubset failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-intake #27721 / part3
• elasticsearch-pull-request #88890 / part-3
• elasticsearch-pull-request #88667 / part-3
• elasticsearch-pull-request #87581 / part-3

Reproduction Line:

./gradlew ":x-pack:plugin:esql:internalClusterTest" --tests "org.elasticsearch.xpack.esql.action.RandomizedTimeSeriesIT.testGroupBySubset" -Dtests.seed=57767CC237ED6261 -Dtests.locale=en-NR -Dtests.timezone=Asia/Dubai -Druntime.java=24

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

org.elasticsearch.action.bulk.IndexDocFailureStoreStatus$ExceptionWithFailureStoreStatus: org.elasticsearch.cluster.metadata.DataStream$TimestampError: the document timestamp [2025-08-29T13:08:12.000Z] is outside of ranges of currently writable indices [[2025-08-29T13:08:13.000Z,2025-08-29T15:38:13.000Z]]

Issue Reasons:

• [main] 4 failures in test testGroupBySubset (1.9% fail rate in 216 executions)
• [main] 3 failures in step part-3 (2.7% fail rate in 113 executions)
• [main] 3 failures in pipeline elasticsearch-pull-request (2.7% fail rate in 113 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] 2 failures in test testGroupBySubset (2.0% fail rate in 101 executions)

Build Scans:

• elasticsearch-intake #27154 / part3
• elasticsearch-periodic #10134 / openjdk23_checkpart3_java-matrix

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)

[kkrik-es]

TSDS rejects duplicate docs, i.e. docs with the same timestamp and tsid. Using unique (e.g. monotonic) timestamps should address this.

[pabloem]

this is fixed by #133489