add pp ref min activity sequence for UT HV scans
This MR:
- Creates a pp ref sequence with the VeloMicroBias line postscaled by 0.1 (instead of 0.001). To be used for UT HV scans, if done at the 1200b fill, the expected rate of the VeloMicroBias line is 1 MHz
- Re-arranges the VeloMicroBias & VeloMicroBiasClosing lines in
HLT1_pp_ref.py
, to be able to change their postscales independently.