Validate FieldInfos count in close in Lucene tests

[ScottDugas]

If addIndexes isn't called, we should be able to have just one FieldInfos, so this test asserts on close that the number of FieldInfos isn't too large.

[foundationdb-ci]

Result of fdb-record-layer-pr on Linux CentOS 7

• Commit ID: 5d31007
• Duration 0:46:01
• Result: ❌ FAILED
• Error: Error while executing command: ./gradlew --no-daemon --console=plain -b ./build.gradle build destructiveTest -PcoreNotStrict -PreleaseBuild=false -PpublishBuild=false -PspotbugsEnableHtmlReport. Reason: exit status 1
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• Build Workspace zip file of the working directory (available for 30 days)