Revert "add (and enable) option to override SPINUP in lhe file for Pythia8 tau decays"
(no longer needed with final pythia 8.200)

This reverts commit 378110cb686a01a70d4857b2b9b434f030655416.
replicate standalone pythia8 behaviour for lhe energy-momentum treatment
Merge pull request #5792 from bendavid/py8200final_73x

Interface changes to go with Pythia 8.200 official release (73x)