[CI] MixedClusterEsqlSpecIT test {grok.ShadowingSubfields SYNC} failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #8707 / 8.13.4_bwc
• elasticsearch-periodic #8707 / 8.12.2_bwc
• elasticsearch-periodic #8689 / 8.12.2_bwc
• elasticsearch-periodic #8689 / 8.11.4_bwc
• elasticsearch-periodic #8683 / 8.12.2_bwc
• elasticsearch-periodic #8677 / 8.12.2_bwc
• elasticsearch-periodic #8659 / 8.12.2_bwc
• elasticsearch-periodic #8653 / 8.12.2_bwc
• elasticsearch-periodic #8653 / 8.11.4_bwc
• elasticsearch-periodic #8641 / 8.11.4_bwc

Reproduction Line:

./gradlew ":x-pack:plugin:esql:qa:server:mixed-cluster:v8.13.4#javaRestTest" -Dtests.class="org.elasticsearch.xpack.esql.qa.mixed.MixedClusterEsqlSpecIT" -Dtests.method="test {keep.ShadowingSubfieldsWildcard SYNC}" -Dtests.seed=A15AE52563A9DEDA -Dtests.bwc=true -Dtests.locale=fr-MC -Dtests.timezone=Africa/Banjul -Druntime.java=24

Applicable branches:
8.19

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: 
Data mismatch:
row 0 column 0:a list containing
row 0 column 0:0: expected "Europe" but was "null"
row 0 column 1:a list containing
row 0 column 1:0: expected "Netherlands" but was "null"
row 0 column 2:a list containing
row 0 column 2:0: expected "Amsterdam" but was "null"
row 0 column 3:a list containing
row 0 column 3:0: expected "Earth" but was "null"
row 1 column 0:a list containing
row 1 column 0:0: expected "North America" but was "null"
row 1 column 1:a list containing
row 1 column 1:0: expected "United States of America" but was "null"
row 1 column 2:a list containing
row 1 column 2:0: expected "San Francisco" but was "null"
row 1 column 3:a list containing
row 1 column 3:0: expected "Earth" but was "null"
row 2 column 0:a list containing
row 2 column 0:0: expected "Asia" but was "null"
row 2 column 1:a list containing
row 2 column 1:0: expected "Japan" but was "null"
row 2 column 2:a list containing
row 2 column 2:0: expected "Tokyo" but was "null"

[truncated]

Issue Reasons:

• [8.19] 2 consecutive failures in test test {grok.ShadowingSubfields SYNC}
• [8.19] 13 failures in test test {grok.ShadowingSubfields SYNC} (1.8% fail rate in 722 executions)
• [8.19] 6 failures in step 8.12.2_bwc (30.0% fail rate in 20 executions)
• [8.19] 6 failures in step 8.11.4_bwc (28.6% fail rate in 21 executions)
• [8.19] 10 failures in pipeline elasticsearch-periodic (47.6% fail rate in 21 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)