Look into how AssumedComplete works for ArjunaJTA (and jtax)

When a transaction cannot be completed over a long period of time, a scanner is supposed to kick in and move the log elsewhere. Those scanners exist in ArjunaCore and ArjunaJTS, but do not appear to be there in ArjunaJTA. It should be straightforward to add them by using the base class in ArjunaCore, but investigate whether they are present already and just not obvious.