Migrate BeamHaloPair configuration
Fix a typo (missing newline)
Migrate GenericPairGenerator and GenericTripletGenerator configuration
Migrate SimpleCosmicBONSeeder to use SeedingLayerSetsHits
Migrate SimpleCosmicBONSeeder configuration
Remove TrackingRegion::hits(..., const ctfseeding::SeedingLayer*)

All callers have been migrated to use the SeedingLayerSetsHits
variant. Removing the method with this signature allows further
TrackingRecHit rework.