test improvements for stream dir and perf opt

- check delete freed in more places
- port similar improvements from file tests to stream tests
fixed and better freed file deletion and tests

- there was a long standing bug where data files that were on the
interior of the file-range of all the streams that spanned them
were never deleted
- it was terribly slow for large numbers of streams due to 4N boxed
hashmap get/puts and double iteration over the stream map. Now it
uses a single iteration over the stream map, a (likely very small)
int array instead of a Integer hashmap, and the array is only
traversed once.
- test cleaned up even more to be clear what it is testing, why, and
where. It also uses more Asserts, and less log spam