Fix muon energy loss bug in MET
This propagates some patches that were put into 21.2 quite a while back but didn't go into master for some reason(04409686 and 70e9cf06). It adjusts the behavior of the muon energy loss calculation in METMaker, fixing what I believe was a bug or two.
Tagging @schae as the original author and @mswiatlo, @maklein for their awareness.