Optimizing the test
Make sure that we start writing from the last written position after restart
Even if there isn't any usable data in a log file, we might still have some usable pages there.
When we have a write transaction that didn't actually write anything, just ignore it from storage & tx id perspectives.
After flushing a log file, forget all about the earlier pages in the log file, use the ones directly from the data file
Fixing copying free space root to root tree entry