Crash in Velo decoding for high-multiplicity events

The segfault can be reproduced by running

from Moore import options, run_reconstruction
from RecoConf.standalone import standalone_hlt2_light_reco

from RecoConf.hlt1_tracking import require_gec, default_ft_decoding_version
from RecoConf.hlt2_tracking import make_hlt2_tracks, all_hlt2_forward_track_types
from RecoConf.mc_checking import monitor_track_resolution

options.evt_max = 1
options.first_evt = 1172
options.set_input_and_conds_from_testfiledb('upgrade-202004-PbPb-EPOS-b-6_14fm')

default_ft_decoding_version.global_bind(value=6)
with standalone_hlt2_light_reco.bind(do_mc_checking=False, do_data_monitoring=False), \
     require_gec.bind(cut=200000),\
     make_hlt2_tracks.bind(use_pr_kf=True):
    run_reconstruction(options, standalone_hlt2_light_reco)

It happens when getting the hits from the raw banks. Nightlies are not affected because they do not run this event and apply a GEC of 40k. Potential source: https://gitlab.cern.ch/lhcb/Rec/-/blob/master/Pr/PrPixel/src/VeloClusterTrackingSIMD.cpp#L149

@ahennequ @gunther @rlitvino @cmarinbe