FPGATrackSim: possible fix for the unit test failure
This may fix the issue reported in EFTRACK-745.
I suspect there is a race condition where the monitoring.root
file is generated by other unit tests as well in the same directory so as a starting point the only change here (apart from renaming the test file for some coherence) is making a sub-directory and running the test in there.
Should get in after !76100 (merged)
cc: @jahreda