updated GTs for 7_2_0_pre1

Updating GTs for 7_2_0 cycle:

- new SiPixelGen errors (for data and MC GTs) 
- new RPC digitizer (for MC GTs)
- new MVA trainings of b-tagging algorithm (data and MC GTs)
- XML geometries fix for Run2 MC GTs
- restoring correct 2D b-tag probabilities for MC GTs