[CI] MixedClusterClientYamlTestSuiteIT class failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #8046 / 8.16.6_bwc
• elasticsearch-periodic #8040 / 8.16.6_bwc
• elasticsearch-periodic #8034 / 8.16.6_bwc
• elasticsearch-periodic #8028 / 8.16.6_bwc
• elasticsearch-periodic #8022 / 8.16.6_bwc
• elasticsearch-periodic #8016 / 8.16.6_bwc
• elasticsearch-periodic #8010 / 8.16.6_bwc
• elasticsearch-periodic #8004 / 8.17.6_bwc
• elasticsearch-periodic #8004 / 8.16.6_bwc
• elasticsearch-periodic #7998 / 8.16.6_bwc

Reproduction Line:

./gradlew ":qa:mixed-cluster:v8.16.6#mixedClusterTest" -Dtests.class="org.elasticsearch.backwards.MixedClusterClientYamlTestSuiteIT" -Dtests.method="test {p0=search/330_fetch_fields/Test with subobjects: auto}" -Dtests.seed=36CC160244BCF2AF -Dtests.bwc=true -Dtests.locale=pt-MZ -Dtests.timezone=Asia/Qyzylorda -Druntime.java=24

Applicable branches:
8.19

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: Failure at [search/330_fetch_fields:1135]: expected [2xx] status code but api [indices.create] returned [400 Bad Request] [{"error":{"root_cause":[{"type":"parse_exception","reason":"unknown subobjects value: auto","stack_trace":"org.elasticsearch.ElasticsearchParseException: unknown subobjects value: auto\n\tat org.elasticsearch.index.mapper.ObjectMapper$Subobjects.from(ObjectMapper.java:86)\n\tat org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseSubobjects(ObjectMapper.java:344)\n\tat org.elasticsearch.index.mapper.RootObjectMapper.parse(RootObjectMapper.java:452)\n\tat org.elasticsearch.index.mapper.MappingParser.parse(MappingParser.java:122)\n\tat org.elasticsearch.index.mapper.MapperService.parseMapping(MapperService.java:609)\n\tat org.elasticsearch.index.mapper.MapperService.doMerge(MapperService.java:565)\n\tat org.elasticsearch.index.mapper.MapperService.merge(MapperService.java:449)\n\tat org.elasticsearch.cluster.metadata.MetadataCreateInd
[truncated]

Issue Reasons:

• [8.19] 20 consecutive failures in step 8.16.6_bwc
• [8.19] 21 failures in class org.elasticsearch.backwards.MixedClusterClientYamlTestSuiteIT (2.2% fail rate in 967 executions)
• [8.19] 20 failures in step 8.16.6_bwc (100.0% fail rate in 20 executions)
• [8.19] 20 failures in pipeline elasticsearch-periodic (100.0% fail rate in 20 executions)

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

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)