Update eFEX isolation threshold logic to match firmware

Following on from https://its.cern.ch/jira/browse/ATR-27796. There we discovered that if the "tightness" of isolation cuts in some regions did not follow the nominal ordering (e.g. the "medium" threshold at some point was tighter than the "tight") you not only get unwanted results but the behaviour of firmware and simulation differs. This then produces false error reports in the monitoring. The reason was changes in one that had not propagated to the other: this made no difference when the ordering of "tightness" was followed, but produced different behaviour when it was not.

This merge changes the simulation to follow the logic of the firmware, and so should remove these false error reports in the monitoring when a menu with this condition is loaded - as is the case presently. And even with a wholly "ordered" menu we would want the threshold logic to be consistent between the simulation and firmware as a matter of principle.