xAOD::TAuxStore Speedup, master branch (2022.08.29.)

Following in the footsteps of !56272 (merged), this MR improves the performance of xAOD::TAuxStore.

This time around I started from a SUSY test job (pointed to be @zmarshal).

SUSYToolsTester \
   /cvmfs/atlas-nightlies.cern.ch/repo/data/data-art/SUSYTools/DAOD_PHYS.mc20_13TeV.410470.FS_mc20e_p5226.PHYS.pool.root \
   maxEvents=2000 isData=0 isAtlfast=0 Debug=0 NoSyst=0 \
   PRWFile=dev/PileupReweighting/mc16_13TeV/pileup_mc16e_dsid410470_FS.root \
   ilumicalcFile=GoodRunsLists/data18_13TeV/20190318/ilumicalc_histograms_None_348885-364292_OflLumi-13TeV-010.root

Which looks like this in the current master branch:

With the updates of this MR this profile is modified to:

String comparisons are still the dominant thing in the job, but they became a lot less prevalent nevertheless. And (drum roll...) the above test job on my machine went from taking ~12 minutes to only taking ~4! With the cutflow printout from the job not changing. 😄

I still have some ideas on how to further improve things, but let's just go one step at a time. 😉