Update track isolation accessor for muons in LeptonTaggers

This MR eliminates the lepton isolation warning

WARNING Lepton isolation not found in auxiliary store

It was discovered that this warning was only generated for muons, not for electrons, because muons were trying to access a non-existent isolation variable.

The r21 accessor ptvarcone30_TightTTVA_pt500 no longer exists in r24. This MR updates the accessor to use the new ptvarcone30_Nonprompt_All_MaxWeightTTVA_pt500 accessor.

See thread at !66768 (comment 7288990)

Also reference the IFF documentation at https://atlas-iff.docs.cern.ch/analysisrecommendations/index.html

Tagging @mvanadia @kzoch @pgadow @nasbah @nbruscin