[CI] FeatureUpgradeApiIT testCreatingSystemIndex failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic-platform-support #7035 / ubuntu-2404-aarch64_checkpart1_platform-support-arm
• elasticsearch-periodic-platform-support #6967 / ubuntu-2404-aarch64_checkpart1_platform-support-arm

Reproduction Line:

./gradlew ":qa:system-indices:javaRestTest" --tests "org.elasticsearch.system.indices.FeatureUpgradeApiIT.testCreatingSystemIndex" -Dtests.seed=CF1E04AD8C11B7F9 -Dtests.locale=frr-DE -Dtests.timezone=Canada/Newfoundland -Druntime.java=23

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

org.elasticsearch.client.ResponseException: method [POST], host [http://[::1]:33029], URI [/_features/_reset], status line [HTTP/1.1 429 Too Many Requests]
{"error":{"root_cause":[{"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (ml-set-reset-mode) within 30s","suppressed":[{"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (transform-set-reset-mode) within 30s"}]}],"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (ml-set-reset-mode) within 30s","suppressed":[{"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (transform-set-reset-mode) within 30s"}]},"status":429}

Issue Reasons:

• [main] 2 failures in test testCreatingSystemIndex (0.4% fail rate in 560 executions)
• [main] 2 failures in step ubuntu-2404-aarch64_checkpart1_platform-support-arm (20.0% fail rate in 10 executions)
• [main] 2 failures in pipeline elasticsearch-periodic-platform-support (20.0% fail rate in 10 executions)

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

[elasticsearchmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[JVerwolf]

This hasn't failed since March. Looking at the message "failed to process cluster event (ml-set-reset-mode) within 30s", I think this was failing due to an unrelated issue that has since been resolved.