[CI] CrossClusterEsqlRCS1MissingIndicesIT testSearchesAgainstNonMatchingIndicesSkipUnavailableTrue failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic-platform-support #9050 / rhel-9_platform-support-unix
• elasticsearch-periodic-platform-support #9022 / windows-2022_checkpart4_platform-support-windows

Reproduction Line:

./gradlew ":x-pack:plugin:security:qa:multi-cluster:javaRestTest" --tests "org.elasticsearch.xpack.remotecluster.CrossClusterEsqlRCS1MissingIndicesIT.testSearchesAgainstNonMatchingIndicesSkipUnavailableTrue" -Dtests.seed=EC2EA533797FF4E9 -Dtests.locale=sr-BA -Dtests.timezone=Africa/Abidjan -Druntime.java=24

Applicable branches:
9.1

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: 
Expected: a string containing "no such index"
     but: was "[][[::1]:36425][indices:data/read/esql/cluster] disconnected"

Issue Reasons:

• [9.1] 2 failures in test testSearchesAgainstNonMatchingIndicesSkipUnavailableTrue (2.4% fail rate in 85 executions)
• [9.1] 2 failures in pipeline elasticsearch-periodic-platform-support (40.0% fail rate in 5 executions)

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

[elasticsearchmachine]

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

[dnhatn]

Fixed in #130292