Fixing thresholds for currents to not read in maps for online, and returning zero b-field if no map is read
Setting returned field value to 0 is no map is loaded, which happens when the solenoid/toroid currents are both below a threshold. And adding in current threshold to map cond alg for current setting via jobOpts.
Related to ATLASRECTS-5604 and ATLASRECTS-5636.
Previously, if no map is read, there is a simple z field set for testing. @masahiro, do you know if this is really used anywhere? It looks like the online would like to have a zero field returned, now.