[CI] EsqlSpecIT test {lookup-join.NonUniqueRightKeyOnTheCoordinator ASYNC} failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-intake #16163 / part3
• elasticsearch-periodic-platform-support #5947 / rocky-8_platform-support-unix

Reproduction Line:

./gradlew ":x-pack:plugin:esql:qa:server:multi-node:javaRestTest" --tests "org.elasticsearch.xpack.esql.qa.multi_node.EsqlSpecIT" -Dtests.method="test {lookup-join.NonUniqueRightKeyOnTheCoordinator ASYNC}" -Dtests.seed=D14087BB524E4536 -Dtests.locale=lkt-US -Dtests.timezone=Europe/Tallinn -Druntime.java=23

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: 
Data mismatch:
row 4 column 3:a list containing
row 4 column 3:0: expected "[Germany, Austria]" but was "null"
row 5 column 3:a list containing
row 5 column 3:0: expected "Switzerland" but was "[Germany, Austria]"
row 6 column 3:a list containing
row 6 column 3:0: expected "null" but was "Switzerland"
Actual:
emp_no:integer | language_code:integer | language_name:keyword | country:text            
10001          | 1                     | English               | Canada                  
10001          | 1                     | English               | null                    
10001          | 1                     | null                  | United Kingdom          
10001          | 1                     | English               | United States of America
10002          | 2                     | German                | null                    
10002          | 2                     | German                | [Germany, Austria]      
10002          | 2              
[truncated]

Issue Reasons:

• [main] 2 failures in test test {lookup-join.NonUniqueRightKeyOnTheCoordinator ASYNC} (0.8% fail rate in 252 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 test {lookup-join.NonUniqueRightKeyOnTheCoordinator ASYNC} (0.8% fail rate in 252 executions)

Build Scans:

• elasticsearch-intake #16163 / part3
• elasticsearch-periodic-platform-support #5947 / rocky-8_platform-support-unix

[elasticsearchmachine]

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