Run Woodcock Tracking in the EMEC rather than EMECPara G4Region by default (ATLASSIM-6426)
Currently we use Woodcock tracking in the "EMECPara" G4Region which consists of a subset
of the volumes in the EMEC envelope. There is also an "EMEC" G4Region which contains the
top-level EMEC volumes. In order to avoid creating the "EMECPara" G4Region as this causes
some potential issues (ATLASSIM-6426), we would like to run Woodcock tracking in the "EMEC"
G4Region instead. This change was validated in ATLPHYSVAL-937.
Currently marked as draft until confirmation of validation sign-off in ATLPHYSVAL-937 and a decision about whether the effect of this change is small enough that it can go into the 23.0 branch or whether it can only go into the master branch.