Allow multi_channel setting

2jetfc.fnl2412eff-fc-v2.run

@@ -27,7 +27,7 @@ RUN @CHANNEL@-CMS7-ak07     ! job name
   reset_vegas_grid = .true.     ! normally true
   lips_reduce      = .true.     ! optimisation for identical particles in FS; normally true
   angular_average  = .true.     ! azimuthal rotation; only relevant for NNLO; can always be true; might be false for RR
-  multi_channel    = 5          ! color sampling; true faster, less precise; true/false must be consistent between warmup & production; can be set to 5 instead of true
+  multi_channel    = @MULTI_CHANNEL@ ! color sampling; true faster, less precise; true/false must be consistent between warmup & production; can be set to 5 instead of true
   @RUNMODE@ = @EVENTS@[@ITERATIONS@] ! Normally #iterations is 1 for production
 END_RUN