Pixel track conf for UPC

Making Pixel tracks configuration consistent with RUN2, for UPC at TrackingPassFlags.py:

• Changing EnableHI flags by PrimaryPassConfig.HeavyIon
• allowing maxPrimaryImpact to by 10 mm if doMinBias

tagging HI conveners @angerami @mrybar @qhu for UPC @mdyndal, expert @tstreble