Remove unused variables from TauIDVarCalculator

This MR is cleaning up the calculation of old variables (Run1, early Run2, R21) in xAODs which are currently not used by any TauCP related algorithm.

This is meant as developments for Run4/eventual xAOD reprocessing, making Tau related containers lighter an without extra not needed content

Tagging @liuya, @salderwe and @martindl for TauCP

Note: xAOD output change is expected from this MR