CI Failures for SLMSnapshotBlockingIntegTests testSnapshotInProgress

[jdconrad]

Reproduce with:

REPRODUCE WITH: ./gradlew ':x-pack:plugin:ilm:test' --tests "org.elasticsearch.xpack.slm.SLMSnapshotBlockingIntegTests.testSnapshotInProgress" \
  -Dtests.seed=65DEEE302AEB2E47 \
  -Dtests.security.manager=true \
  -Dtests.locale=hsb-DE \
  -Dtests.timezone=America/Indiana/Petersburg \
  -Dcompiler.java=12 \
  -Druntime.java=12

REPRODUCE WITH: ./gradlew ':x-pack:plugin:ilm:test' --tests "org.elasticsearch.xpack.slm.SLMSnapshotBlockingIntegTests.testSnapshotInProgress" \
  -Dtests.seed=65DEEE302AEB2E47 \
  -Dtests.security.manager=true \
  -Dtests.locale=hsb-DE \
  -Dtests.timezone=America/Indiana/Petersburg \
  -Dcompiler.java=12 \
  -Druntime.java=12

from (https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+master+matrix-java-periodic/ES_BUILD_JAVA=openjdk12,ES_RUNTIME_JAVA=openjdk12,nodes=general-purpose/251/console)

https://gradle-enterprise.elastic.co/s/cc7dkdd6bvbfs

[elasticmachine]

Pinging @elastic/es-core-features (:Core/Features/ILM+SLM)

[jimczi]

The test is now muted in master and 7x.