ISPN-4733 Investigate potential issues with System.nanoTime() overflow

* Fixed TestingUtil calculation for when to stop trying
* Changed stats to not error if nanotime is -1 (extreme edge case)
* Also fixed TransactionTable when clearing old txs
ISPN-4137 Transaction executed multiple times due to forwarded CommitCommand

Make rollback commands synchronous
Move stuff from AbstraceEnlistmentAdapter to TransactionCoordinator.