[CI] TimestampFormatFinderTests.testGuessIsDayFirstFromLocale can fail in FIPS JVM

[droberts195]

TimestampFormatFinderTests.testGuessIsDayFirstFromLocale has failed twice in the last few days in the FIPS JVM, due to thinking that the default date format in France has month before day.

Both failures are in the 7.3 branch:

• https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+7.3+matrix-java-periodic/ES_BUILD_JAVA=openjdk12,ES_RUNTIME_JAVA=java8fips,nodes=general-purpose/57/console
• https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+7.3+matrix-java-periodic/ES_BUILD_JAVA=openjdk12,ES_RUNTIME_JAVA=java8fips,nodes=general-purpose/59/console

The repro commands are:

./gradlew :x-pack:plugin:ml:test --tests "org.elasticsearch.xpack.ml.filestructurefinder.TimestampFormatFinderTests.testGuessIsDayFirstFromLocale" \
  -Dtests.seed=1E4D93397AE88FF6 \
  -Dtests.security.manager=true \
  -Dtests.locale=lt-LT \
  -Dtests.timezone=Africa/Nouakchott \
  -Dcompiler.java=12 \
  -Druntime.java=8FIPS \
  -Djavax.net.ssl.keyStorePassword=password \
  -Djavax.net.ssl.trustStorePassword=password

and:

./gradlew :x-pack:plugin:ml:test --tests "org.elasticsearch.xpack.ml.filestructurefinder.TimestampFormatFinderTests.testGuessIsDayFirstFromLocale" \
  -Dtests.seed=BCBB21C07C9887DC \
  -Dtests.security.manager=true \
  -Dtests.locale=fr-CH \
  -Dtests.timezone=America/Porto_Velho \
  -Dcompiler.java=12 \
  -Druntime.java=8FIPS \
  -Djavax.net.ssl.keyStorePassword=password \
  -Djavax.net.ssl.trustStorePassword=password

I will selectively mute the non-US locales, similar to what was done in #38265 and #39052.

[elasticmachine]

Pinging @elastic/ml-core