[CI] SearchableSnapshotActionIT testConvertingSearchableSnapshotFromFullToPartial failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #7545 / concurrent-search-tests
• elasticsearch-periodic #7440 / single-processor-node-tests

Reproduction Line:

./gradlew ":x-pack:plugin:ilm:qa:multi-node:javaRestTest" --tests "org.elasticsearch.xpack.ilm.actions.SearchableSnapshotActionIT.testConvertingSearchableSnapshotFromFullToPartial" -Dtests.seed=6ADBECFE16B1790E -Dtests.jvm.argline="-Des.concurrent_search=true" -Dtests.locale=prg -Dtests.timezone=Europe/Zurich -Druntime.java=24

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: null

Issue Reasons:

• [main] 2 failures in test testConvertingSearchableSnapshotFromFullToPartial (0.3% fail rate in 705 executions)
• [main] 2 failures in pipeline elasticsearch-periodic (12.5% fail rate in 16 executions)

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

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[nielsbauman]

Yet another one (just like #125789 and #125867) that is stuck in the wait-for-index-color ILM step. #125812 adds a workaround for this, but we're currently still discussing potential other options.