Fix problems with KeystoreManagementTests#test51WrongKeystorePasswordFromFile

[williamrandolph]

On the cleaned-up feature branch for the password-protected keystore, there are two problems with one of our packaging tests: first, it fails occasionally, and second, it doesn't clean up after itself when it does, so a bunch of later tests also fail.

It's not yet clear to me why this test fails, but when it does, the stack trace is:

java.lang.AssertionError: 

Expected: a string containing "Provided keystore password was incorrect"
     but: was "<<Too large to read: 105340 bytes>>"

at __randomizedtesting.SeedInfo.seed([264C6E7CFA0C535D:F86B07EA259CE6AE]: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.PackagingTestCase.assertElasticsearchFailure(PackagingTestCase.java:307)
at org.elasticsearch.packaging.test.KeystoreManagementTests.test51WrongKeystorePasswordFromFile(KeystoreManagementTests.java:247)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:566)
at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1750)
at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:938)
at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:974)
at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:988)
at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:368)
at java.lang.Thread.run(Thread.java:834)

Relates #32691

[elasticmachine]

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