Add postInclude to reproduce MC16/MC20 EMEC geometry configuration

This can be used to get back the MC16/MC20 performance once we change the default in the C++ to the "Slices" variant.

FYI @mbandier, @tadej

Simulation/SimulationJobOptions/share/g4/postInclude.MC16_EMEC_Setup.py

+###########################################################
+#
+# EMEC custom solid WHEEL variant
+# Use the WHEEL variant of the EMEC custom solid
+# both for the inner and outer wheel as in MC16/MC20.
+# More info: https://its.cern.ch/jira/browse/ATLASSIM-3778
+#
+###########################################################
+
+from LArGeoAlgsNV.LArGeoAlgsNVConf import LArDetectorToolNV
+LArDetectorToolNV.EMECVariantInner="Wheel"
+LArDetectorToolNV.EMECVariantOuter="Wheel"