[CI] MixedClusterEsqlSpecIT test {string.EndsWithLucenePushdownIgnoreMultivalues ASYNC} failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #6990 / 8.14.3_bwc
• elasticsearch-periodic #6976 / 8.14.3_bwc
• elasticsearch-periodic #6948 / 8.14.3_bwc
• elasticsearch-periodic #6941 / 8.14.3_bwc

Reproduction Line:

./gradlew ":x-pack:plugin:esql:qa:server:mixed-cluster:v8.14.3#javaRestTest" -Dtests.class="org.elasticsearch.xpack.esql.qa.mixed.MixedClusterEsqlSpecIT" -Dtests.method="test {string.EndsWithLucenePushdownIgnoreMultivalues SYNC}" -Dtests.seed=AFDA69177808A303 -Dtests.bwc=true -Dtests.locale=bm-ML -Dtests.timezone=Etc/GMT-14 -Druntime.java=24

Applicable branches:
8.x

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: Unexpected warning: Line -1:-1: evaluation of [] failed, treating result as null. Only first 20 failures recorded.

Issue Reasons:

• [8.x] 4 failures in test test {string.EndsWithLucenePushdownIgnoreMultivalues ASYNC} (0.9% fail rate in 441 executions)
• [8.x] 4 failures in step 8.14.3_bwc (50.0% fail rate in 8 executions)
• [8.x] 4 failures in pipeline elasticsearch-periodic (50.0% fail rate in 8 executions)

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

[elasticsearchmachine]

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

[ivancea]

Fixed in #124764