Track folder does not get deleted if exception occurs during upload

We do have the TrackDataManager with its commit/rollback functionality, but if we get an exception after we've created the data directory but before we actually commit the SQL transaction, the data directory exists but the track doesn't. This will prevent future tracks from being uploaded, as the ID might get re-used but the track data directory exists.

I've noticed this because adding the track to the hittekaart queue failed, so there's a chance this might happen.