Upper limit for cell time cut application propagated back from master

A cell time cut has been added to cluster making stage:!36860 (merged). We then added an option for restricting the time cut to seed cells with E/sigma smaller than a given threshold. In order to meet the last feature freeze, this option was added into the master branch first: !37522 (merged). With this MR we are propagating it back to r21: it is needed to finalise the testing and for easier comparison with previous results in r21. All options are switched off by default and can be turned on at preExec.