Pdigitizer merging curr upg 3

Porting the pixel-aging feature used in 62XSLHC branch by pixel digitizer (for upgrade studies) to 73X. 
Deleting the pseudoRadDamage variables since they are not used.
Some indent corrections in drift () function ( SimTracker/SiPixelDigitizer/plugins/SiPixelDigitizerAlgorithm.cc ).