Add postInclude to force use of Module level Pixel Masking
After !45356 (merged) it is useful to be able to force the use of Module-level Pixel Masking for older conditions tags via a postInclude.
This merge request includes an example fix in the form of Simulation/Tests/DigitizationTests/test/test_Digi_tf_mc15_2015_heavy_ion.sh
This should fix ATLASSIM-5365.