[CI] DockerTests.test085EnvironmentVariablesAreRespectedUnderDockerExec fails with missing keystore file

[tlrx]

This test DockerTests.test085EnvironmentVariablesAreRespectedUnderDockerExec fails everyday on master, 7.11, 7.10 or 7.x. Another issue #66656 is opened for this test but the error is different so I'm opening a new issue.

Build scans:
https://gradle-enterprise.elastic.co/s/jkuoddwnkjkzs
https://gradle-enterprise.elastic.co/s/pxr65mf6xmhqs
https://gradle-enterprise.elastic.co/s/gy5sbg4msiycw

Applicable branches:
master, 7.x, 7.11 and 7.10

Failure history:
Build history shows many failures over the last month.

Failure excerpt:

org.elasticsearch.packaging.test.DockerTests > test085EnvironmentVariablesAreRespectedUnderDockerExec FAILED
    java.lang.AssertionError: 
    Expected: a string containing "java.net.UnknownHostException: this.is.not.valid: Name or service not known"
         but: was "ERROR: Elasticsearch keystore file is missing [/usr/share/elasticsearch/config/elasticsearch.keystore]"
        at __randomizedtesting.SeedInfo.seed([23D04474A3D733E1:857F2D053C98986E]:0)
        at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
        at org.junit.Assert.assertThat(Assert.java:956)
        at org.junit.Assert.assertThat(Assert.java:923)
        at org.elasticsearch.packaging.test.DockerTests.test085EnvironmentVariablesAreRespectedUnderDockerExec(DockerTests.java:486)

[elasticmachine]

Pinging @elastic/es-delivery (Team:Delivery)