[CI] CoreWithMultipleProjectsClientYamlTestSuiteIT test {yaml=search.vectors/90_sparse_vector/Indexing and searching multi-value sparse vectors in >=8.15} failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #10229 / openjdk21_checkpart2_java-matrix
• elasticsearch-pull-request #86639 / part-2

Reproduction Line:

./gradlew ":x-pack:qa:multi-project:core-rest-tests-with-multiple-projects:yamlRestTest" --tests "org.elasticsearch.multiproject.test.CoreWithMultipleProjectsClientYamlTestSuiteIT" -Dtests.method="test {yaml=search.vectors/90_sparse_vector/Indexing and searching multi-value sparse vectors in >=8.15}" -Dtests.seed=C97B10A552F32B40 -Dtests.locale=twq-NE -Dtests.timezone=W-SU -Druntime.java=21

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: Failure at [search.vectors/90_sparse_vector:313]: 
Expected: <3>
     but: was <2>

Issue Reasons:

• [main] 2 failures in test test {yaml=search.vectors/90_sparse_vector/Indexing and searching multi-value sparse vectors in >=8.15} (0.3% fail rate in 719 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 {yaml=search.vectors/90_sparse_vector/Indexing and searching multi-value sparse vectors in >=8.15} (0.3% fail rate in 719 executions)

Build Scans:

• elasticsearch-periodic #10229 / openjdk21_checkpart2_java-matrix
• elasticsearch-pull-request #86639 / part-2

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[elasticsearchmachine]

Pinging @elastic/es-search-relevance (Team:Search Relevance)

[john-wagster]

ran the test multiple times locally and can't reproduce this. Not sure how it got into this state.