Fix always switching back to mgun in Q3 controls menu

Caused by 120e296a74b0317f29d7f516d904bdc70f71b006.
Fix Gauntlet barrel axis in UI

UI's PositionRotatedEntityOnTag is different than CGame's and
UI has switched pitch/roll for Gauntlet/BFG axis to get it to
look like /close to/ how it looks in CGame.

Making UI use the same *PositionRotatedEntityOnTag and axis as
CGame fixes the Gauntlet blade being wobbly in controls menu.