[CI] MultiClustersIT testLookupJoinAliasesSkipOld failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #9524 / openjdk21_9.1.0_java-fips-matrix-bwc
• elasticsearch-pull-request #81696 / 9.0.4_part_3_bwc-snapshots

Reproduction Line:

./gradlew ":x-pack:plugin:esql:qa:server:multi-clusters:v9.1.0#newToOld" -Dtests.class="org.elasticsearch.xpack.esql.ccq.MultiClustersIT" -Dtests.method="testLookupJoinAliasesSkipOld" -Dtests.seed=ED428BC30A3042F8 -Dtests.bwc=true -Dtests.locale=smn -Dtests.timezone=Pacific/Gambier -Druntime.java=21 -Dtests.fips.enabled=true

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: Expected a map containing
documents_found: <445>
  values_loaded: <445>
           took: <124>
      _clusters: <{running=0, total=2, details={remote_cluster={_shards={total=0, failed=0, successful=0, skipped=0}, took=30, indices=test-remote-index, failures=[{reason={reason=remote cluster [remote_cluster] has version [9112003] that does not support multiple indices in LOOKUP JOIN, skipping, type=verification_exception}, index=null, shard=-1}], status=skipped}, (local)={_shards={total=3, failed=0, successful=3, skipped=0}, took=124, indices=test-local-index, status=successful}}, failed=0, partial=0, successful=1, skipped=1}>
     is_partial: <true>
        columns: a list containing
                0: a map containing
               type: "long"
               name: "c"
         values: a list containing
                0: a list containing
                  0: expected <445> but was <446>
        profile: <{planning={took_millis=30, start_millis=1753192066680,
[truncated]

Issue Reasons:

• [main] 2 failures in test testLookupJoinAliasesSkipOld (0.2% fail rate in 855 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 testLookupJoinAliasesSkipOld (0.2% fail rate in 855 executions)

Build Scans:

• elasticsearch-periodic #9524 / openjdk21_9.1.0_java-fips-matrix-bwc
• elasticsearch-pull-request #81696 / 9.0.4_part_3_bwc-snapshots

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[smalyshev]

This is weird - somehow count() produces an extra count. No idea what could cause a thing like that?