Several LogsdbTestSuiteIT yaml REST tests in the 20_ignored_source suite fail in the release-tests pipeline (-Dbuild.snapshot=false).

Failing tests (9):

• test {yaml=/20_ignored_source/fetch stored fields by name}
• test {yaml=/20_ignored_source/fetch fields by name}
• test {yaml=/20_ignored_source/fields and stored fields combination}
• test {yaml=/20_ignored_source/fields with ignored source in stored fields}
• test {yaml=/20_ignored_source/fields with ignored source in fields}
• test {yaml=/20_ignored_source/ignored source via fields and wildcard stored fields}
• test {yaml=/20_ignored_source/wildcard fields and ignored source via stored fields}
• test {yaml=/20_ignored_source/ignored source array via fields}
• test {yaml=/20_ignored_source/ignored source array via stored_fields}

Reproduce:

./gradlew :x-pack:plugin:logsdb:yamlRestTest --tests "org.elasticsearch.xpack.logsdb.LogsdbTestSuiteIT" -Dbuild.snapshot=false -Dtests.jvm.argline="-Dbuild.snapshot=false"

Root cause: Byte array assertion mismatches in _ignored_source binary representation. The expected binary values in the yaml tests no longer match what the server produces, likely related to #143784 ("Store ignored source in binary doc values").

Example failure:

Expected: [<2b>, <0b>, <0b>, <0b>, <105b>, <100b>, <83b>, <102b>, <53b>, <116b>, <55b>, <45b>, <54b>, <54b>, <103b>, <116b>]
     but: was [<1b>, <2b>, <105b>, <100b>, <0b>, <10b>, <83b>, <102b>, <53b>, <116b>, <55b>, <45b>, <54b>, <54b>, <103b>, <116b>]

Build scan: https://gradle-enterprise.elastic.co/s/lbmck4blccdne
Observed in: #144470