[CI] MixedClusterEsqlSpecIT class failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #8779 / 8.12.2_bwc
• elasticsearch-periodic #8773 / 8.11.4_bwc
• elasticsearch-periodic #8749 / 8.11.4_bwc
• elasticsearch-periodic #8743 / 8.11.4_bwc
• elasticsearch-periodic #8737 / 8.11.4_bwc
• elasticsearch-periodic #8737 / 8.12.2_bwc
• elasticsearch-periodic #8737 / 8.13.4_bwc
• elasticsearch-periodic #8731 / 8.13.4_bwc
• elasticsearch-periodic #8731 / 8.11.4_bwc
• elasticsearch-periodic #8725 / 8.11.4_bwc

Reproduction Line:

./gradlew ":x-pack:plugin:esql:qa:server:mixed-cluster:v8.12.2#javaRestTest" -Dtests.class="org.elasticsearch.xpack.esql.qa.mixed.MixedClusterEsqlSpecIT" -Dtests.method="test {string.MvStringEqualsLongString SYNC}" -Dtests.seed=83688484BB8817AE -Dtests.bwc=true -Dtests.locale=sah-RU -Dtests.timezone=Pacific/Tongatapu -Druntime.java=24

Applicable branches: 8.19

Reproduces locally?: N/A

Failure History: See dashboard

Failure Message:

java.lang.AssertionError: Expected a list containing
0: expected "Line 2:9: evaluation of [message == \\\"More than one hundred characters long so it isn't indexed by the sub keyword field with ignore_above:100\\\"] failed, treating result as null. Only first 20 failures recorded." but was <missing>
1: expected "Line 2:9: java.lang.IllegalArgumentException: single-value function encountered multi-value" but was <missing>

Issue Reasons:

• [8.19] 125 failures in class org.elasticsearch.xpack.esql.qa.mixed.MixedClusterEsqlSpecIT (17.4% fail rate in 719 executions)
• [8.19] 15 failures in step 8.12.2_bwc (68.2% fail rate in 22 executions)
• [8.19] 4 failures in step openjdk17_8.18.3_java-fips-matrix-bwc (19.0% fail rate in 21 executions)
• [8.19] 4 failures in step openjdk17_8.18.3_java-matrix-bwc (19.0% fail rate in 21 executions)
• [8.19] 6 failures in step openjdk21_8.18.3_java-matrix-bwc (28.6% fail rate in 21 executions)
• [8.19] 5 failures in step graalvm-ce17_8.18.3_java-matrix-bwc (23.8% fail rate in 21 executions)
• [8.19] 5 failures in step openjdk22_8.18.3_java-matrix-bwc (23.8% fail rate in 21 executions)
• [8.19] 6 failures in step openjdk23_8.18.3_java-matrix-bwc (28.6% fail rate in 21 executions)
• [8.19] 3 failures in step 8.18.3_bwc (15.0% fail rate in 20 executions)
• [8.19] 6 failures in step 8.14.3_bwc (30.0% fail rate in 20 executions)
• [8.19] 5 failures in step 8.13.4_bwc (23.8% fail rate in 21 executions)
• [8.19] 17 failures in step 8.11.4_bwc (85.0% fail rate in 20 executions)
• [8.19] 49 failures in step 8.18.3_bwc-snapshots (31.8% fail rate in 154 executions)
• [8.19] 19 failures in pipeline elasticsearch-periodic (86.4% fail rate in 22 executions)
• [8.19] 10 failures in pipeline elasticsearch-intake (20.8% fail rate in 48 executions)

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