x hits not sorted in PrForwardTracking

This crash happened after running more than a day with the TESTBEAMGUI on 40 logical cores:

TESTBEAMGUI_N8190401_HLT2_0: ../Pr/PrAlgorithms/src/PrForwardTracking.cpp:2067: auto LHCb::Pr::Forward::PrForwardTracking<TrackType>::forwardTracks(const TrackType&, const Hits&, const ZoneCache&, const DeMagnet&) const [with TrackType = LHCb::Pr::Velo::Tracks; LHCb::Pr::FT::Hits = LHCb::Pr::Hits<LHCb::Pr::HitType::FT>; LHCb::Pr::Forward::{anonymous}::ZoneCache = FTZoneCache::ZoneCache; DeMagnet = LHCb::Detector::DeMagnet]: Assertion `[&] { const auto coords = LHCb::make_span( allXHits.data<ModSciFiHits::HitTag::coord>(), allXHits.size() ); return std::is_sorted( coords.begin(), coords.end() ); }()' failed.

We can probably afford to just skip the event if this happens.