LuceneIndexTest.simpleInsertDeleteAndSearch is flaky

[ScottDugas]

LuceneIndexTest.simpleInsertDeleteAndSearch is flaky, I've seen it fail a few times with no relevant changes in https://github.com/FoundationDB/fdb-record-layer/pull/1660 with:

LuceneIndexTest > simpleInsertDeleteAndSearch() FAILED
    org.opentest4j.AssertionFailedError: expected: <true> but was: <false>
        at org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
        at org.junit.jupiter.api.AssertTrue.assertTrue(AssertTrue.java:40)
        at org.junit.jupiter.api.AssertTrue.assertTrue(AssertTrue.java:35)
        at org.junit.jupiter.api.Assertions.assertTrue(Assertions.java:162)
        at com.apple.foundationdb.record.lucene.LuceneIndexTest.assertOnlyCompoundFileExisting(LuceneIndexTest.java:1648)
        at com.apple.foundationdb.record.lucene.LuceneIndexTest.assertEntriesAndSegmentInfoStoredInCompoundFile(LuceneIndexTest.java:1640)
        at com.apple.foundationdb.record.lucene.LuceneIndexTest.simpleInsertDeleteAndSearch(LuceneIndexTest.java:616)