Cleaned up VeloHeavyFlavourTracking to use float rather than scalar::float_v
scalar::float_v should in general not be used as member of a class. There you have either a generic float_v in case SIMD is used or float in case not. Due to several other factors, the usage of float_v here did break the C++20 builds, this fixes it
Requires LHCb!4414 (merged)
Edited by Sebastien Ponce