[CI] ServiceAccountSingleNodeTests testAuthenticateWithServiceFileToken failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic-platform-support #6523 / windows-2022_checkpart4_platform-support-windows
• elasticsearch-periodic-platform-support #6509 / windows-2022_checkpart4_platform-support-windows
• elasticsearch-periodic-platform-support #6495 / rocky-8_platform-support-unix
• elasticsearch-periodic-platform-support #6432 / windows-2022_checkpart4_platform-support-windows
• elasticsearch-periodic-platform-support #6376 / windows-2022_checkpart4_platform-support-windows

Reproduction Line:

gradlew ":x-pack:plugin:security:internalClusterTest" --tests "org.elasticsearch.xpack.security.authc.service.ServiceAccountSingleNodeTests.testAuthenticateWithServiceFileToken" -Dtests.seed=2EFC75B55F7ADC71 -Dtests.locale=ko-KR -Dtests.timezone=Africa/Casablanca -Druntime.java=23

Applicable branches:
8.18

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

org.elasticsearch.action.UnavailableShardsException: at least one search shard for the index [.security-7] is unavailable

Issue Reasons:

• [8.18] 5 failures in test testAuthenticateWithServiceFileToken (0.6% fail rate in 895 executions)
• [8.18] 4 failures in step windows-2022_checkpart4_platform-support-windows (19.0% fail rate in 21 executions)
• [8.18] 5 failures in pipeline elasticsearch-periodic-platform-support (22.7% fail rate in 22 executions)

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

[elasticsearchmachine]

Pinging @elastic/es-security (Team:Security)