Reduce the noise in logs due to following log message: https://github.com/mongodb/mongo/blob/069b34c332ea7e8330759037df7bc4bc7d207f2f/src/mongo/db/storage/wiredtiger/wiredtiger_index.cpp#L1166
This log message is useful when debugging and verifying the index data format in 4.0. It would be good to retain it, but could be moved to index traces.