TriggerJobOpts: migrate database modifiers to PostExec
Migrate the dbmod_BFieldAutoConfig.py
include file to CA. This is used during debug stream recovery to overwrite the fixed magnetic field in the SMK with an auto-configured one.
Usage: athenaHLT ... -C 'from TriggerJobOpts import PostExec; PostExec.dbmod_BFieldAutoConfig()'
Also delete the remaining unused modifiers.
cc @mark