TrigInDetTrackFitter magnetic field migration - ATR-21310

Migrate TrigInDetTrackFitter to new magnetic field cache. Also, TrigL2ResidualCalculator shared most of its code with TrigInDetTrackFitter - add the getUnbiasedResiduals method to TrigInDetTrackFitter and delete the tool.

Mysteriously in my local tests this led to muCombMT complaining about being unable to retrieve its field service:

muCombMT_Muon_FTF                              0   ERROR Could not retrieve AtlasFieldSvc --> Abort
muCombMT_Muon_FTF                              0   ERROR AthenaBaseComps/AthenaBaseComps/AthCommonDataStore.icc:43 (StatusCode AthCommonDataStore<PBASE>::sysInitialize() [with PBASE = AthCommonMsg<Algorithm>]):
l2muCombViewNode                               0   ERROR Unable to initialize Algorithm muCombMT/muCombMT_Muon_FTF

I don't know what's going on here so decided to submit the MR anyway. Maybe muCombMT is somehow relying on the AtlasFieldSvc initialised by TrigInDetTrackFitter up to this point?

Cheers,

Stewart