[CI] UpdateThreadPoolSettingsTests testFixedExecutorType failure

[astefan]

Build scan: https://gradle-enterprise.elastic.co/s/safmn5nukss7y

Repro line: ./gradlew ':server:test' --tests "org.elasticsearch.threadpool.UpdateThreadPoolSettingsTests.testFixedExecutorType" -Dtests.seed=314CD7EE34B70039 -Dtests.security.manager=true -Dtests.locale=sq -Dtests.timezone=Australia/Sydney -Druntime.java=8

Reproduces locally?: No

Applicable branches: 7.x

Failure history: failed 5 times in the last 30 days. First failure on Sept 23rd.

Failure excerpt:

org.elasticsearch.threadpool.UpdateThreadPoolSettingsTests > testFixedExecutorType FAILED
    java.lang.IllegalArgumentException: Failed to parse value [15] for setting [thread_pool.system_write.size] must be <= 13
        at __randomizedtesting.SeedInfo.seed([314CD7EE34B70039:18FECDC3778D68C]:0)
        at org.elasticsearch.common.settings.Setting.parseInt(Setting.java:1260)
        at org.elasticsearch.common.settings.Setting.parseInt(Setting.java:1249)
        at org.elasticsearch.threadpool.FixedExecutorBuilder.lambda$new$1(FixedExecutorBuilder.java:117)
        at org.elasticsearch.common.settings.Setting.get(Setting.java:441)
        at org.elasticsearch.common.settings.Setting.get(Setting.java:435)
        at org.elasticsearch.threadpool.FixedExecutorBuilder.getSettings(FixedExecutorBuilder.java:131)
        at org.elasticsearch.threadpool.FixedExecutorBuilder.getSettings(FixedExecutorBuilder.java:38)
        at org.elasticsearch.threadpool.ThreadPool.<init>(ThreadPool.java:214)
        at org.elasticsearch.threadpool.UpdateThreadPoolSettingsTests.testFixedExecutorType(UpdateThreadPoolSettingsTests.java:107)

[elasticmachine]

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

[rjernst]

It looks like this started failing right after #61655 was merged. @jaymode Can you take a look? My hunch is this randomly fails when the new SYSTEM_WRITE thread pool gets randomly selected in this test.

[cbuescher]

Another one today on 7.10: https://gradle-enterprise.elastic.co/s/xklyf67werd5c