Mag field cache fixes unit test and mu sim no toroid
There is a fix and feature addition in the MR:
The fixes is for the unit test in InDetVKalVxInJetTool that had to be commented out in MR !32405 (merged) due to migrating the magField to the new conditions algs/obj/cache. This is fixed by adding to unit test the creation of the AtlasFieldCacheCondObj to get the AtlasFieldCache, and the AtlasFieldCache now will return a constant b-field for tests if no map is found. This is useful for unit tests.
The feature addition is to allow the setting of the toroid current off in a sim job, and have the downstream jobs maintain the knowledge of the changed current to use the correct field maps. This refers to the Jira: https://its.cern.ch/jira/browse/ATLASRECTS-2127. This is done via the use of TagInfo in AtlasFieldMapCondAlg as suggested by @tsulaia.
Finally, there is a bit of cleanup of the UseNewBfieldCache which has been removed in most places, except for AtlasFieldCache which still has a few clients which use it - but will be changed. This may affect FastShowerCellBuilderTool_test in Simulation/FastShower/FastCaloSim and may need it's ref file updated. @jchapman.