Cleaning not attempted if there is no job number 1

[OlivierBondu]

reported by @swertz

see https://github.com/cp3-llbb/GridIn/blob/master/scripts/cleanOldFrameworkTasksNotInDB.py#L174
and https://github.com/cp3-llbb/GridIn/blob/master/scripts/cleanOldFrameworkTasksNotInDB.py#L187