Fix tests to not ignore ordering and also assert all data is present

If we change the policy of timestamp in filename (we would need some other way to embed that logfile-metadata), then this unit test will catch that error. So this should be good. 

Regarding millisecond level accuracy I have observed (maybe for old hadoop versions) while building filestream() that the HDFS api returned mod times at the granularity of seconds. That led to a lot of complexity. And independent of that, who knows, there maybe a slim chance that two files have same mod time, same ms. Thats non-determinism in unit test.