[CI] MixedClusterClientYamlTestSuiteIT test {p0=search.vectors/160_knn_query_missing_params/kNN query in a bool clause - missing num_candidates} failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #5895 / 8.14.3_bwc
• elasticsearch-periodic #5895 / 8.13.4_bwc
• elasticsearch-periodic #5890 / 8.13.4_bwc

Reproduction Line:

./gradlew ":qa:mixed-cluster:v8.14.3#mixedClusterTest" -Dtests.class="org.elasticsearch.backwards.MixedClusterClientYamlTestSuiteIT" -Dtests.method="test {p0=search.vectors/160_knn_query_missing_params/kNN query with missing num_candidates param - size provided}" -Dtests.seed=37E3771D909F6082 -Dtests.bwc=true -Dtests.locale=ti-Ethi-ET -Dtests.timezone=Europe/Nicosia -Druntime.java=23

Applicable branches:
8.x

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: Failure at [search.vectors/160_knn_query_missing_params:94]: expected [2xx] status code but api [search] returned [400 Bad Request] [{"error":{"root_cause":[{"type":"x_content_parse_exception","reason":"[1:67] [knn] unknown field [k]","stack_trace":"org.elasticsearch.ElasticsearchException$1: [1:67] [knn] unknown field [k]\n\tat org.elasticsearch.server@8.14.3/org.elasticsearch.ElasticsearchException.guessRootCauses(ElasticsearchException.java:704)\n\tat org.elasticsearch.server@8.14.3/org.elasticsearch.ElasticsearchException.generateFailureXContent(ElasticsearchException.java:632)\n\tat org.elasticsearch.server@8.14.3/org.elasticsearch.rest.RestResponse.build(RestResponse.java:184)\n\tat org.elasticsearch.server@8.14.3/org.elasticsearch.rest.RestResponse.<init>(RestResponse.java:143)\n\tat org.elasticsearch.server@8.14.3/org.elasticsearch.rest.RestResponse.<init>(RestResponse.java:114)\n\tat org.elasticsearch.server@8.14.3/org.elasticsearch.rest.RestControlle
[truncated]

Issue Reasons:

• [8.x] 2 consecutive failures in test test {p0=search.vectors/160_knn_query_missing_params/kNN query in a bool clause - missing num_candidates}
• [8.x] 2 consecutive failures in step 8.13.4_bwc
• [8.x] 3 failures in test test {p0=search.vectors/160_knn_query_missing_params/kNN query in a bool clause - missing num_candidates} (2.6% fail rate in 114 executions)
• [8.x] 2 failures in step 8.13.4_bwc (100.0% fail rate in 2 executions)
• [8.x] 2 failures in pipeline elasticsearch-periodic (100.0% fail rate in 2 executions)

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

[elasticsearchmachine]

Pinging @elastic/es-delivery (Team:Delivery)

[cbuescher]

@elastic/es-search-relevance these yaml tests still fail on 8.x (and several more that don't have an individual issue assigned yet).
Just wanted to make you aware that I'm trying to mute those in #120462, hopefully caught most of them.