Spin off of SOLR-4934. We should updated tests to ensure that the various ways of specifying useCompoundFile as well as the expected default are working properly after LUCENE-5038
I am seeing RecoveryZkTest and ChaosMonkeySafeLeaderTest fail often on trunk.
Prevent runtime failure if users use initargs "useCompoundFile" setting on LogMergePolicy or TieredMergePolicy
useCompoundFile should default to true like Lucene
Don't call MergePolicy / IndexWriter during DWPT Flush