2024 Magnet Off request with nu=1.6

Closes lhcb-simulation/mc-productions-setup#19

Stage6 file created with

#!/bin/bash
cat <<EOF > magup.stage0.yaml
sim-version: 10

name: Magnet off production
inform:
  - hawu
WG: RTA
file-format: DIGI

samples:
  - event-types:
      - 30000000 # MinBias
      - 12143001 # B+ -> J/psi K+
    magnet-polarities:
      - MagUp
    data-types:
      - 2024.Q1.2
    pileup-nu: 1.6
    num-events: 10k

EOF
lb-mc magup.stage0.yaml magoff.stage6.yaml
yq '.[].name |= sub("MagUp", "MagOff")' -i magoff.stage6.yaml # Request name
yq '.[].sim_condition |= sub("MagUp", "MagOff")' -i magoff.stage6.yaml # Sim condition
yq '.[].steps[0].name |= sub("MagUp", "MagOff")' -i magoff.stage6.yaml # Gauss step name
yq '.[].steps[0].options[0] |= sub("mu100", "moff")' -i magoff.stage6.yaml # Gauss beam options file
yq '.[].steps[].options += ["$APPCONFIGOPTS/Conditions/MagnetOff.py"]' -i magoff.stage6.yaml # Magnet-off options file (overrides conditions)