Draft: (Re) New fastest track reconstruction sequence with UT

Resuscitate !2251 (closed) to check possible improvement on PbPb ghost rate that is quite high with baseline reco.

almost identical to former one.

"This configures a new fastest track reconstruction sequence using the VeloUT tracking in filter mode, i.e. passing through most VELO tracks, as input to the Forward tracking. The Forward tracking uses the momentum estimate of the Upstream track, if available, to narrow its hit search window, gaining almost a factor 3 in throughput. In preliminary tests, this, and a reduction in ghost rate, improves the throughput of the track-reconstruction sequence by about 10%. It also recovers some of the tracks lost previously in the fastest sequence."

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