[test][ff][ms] Use constant time step size

test/freeflow/navierstokesnc/maxwellstefan/params.input

 [TimeLoop]
-DtInitial = 1 # [s]
+DtInitial = 1e5 # [s]
 TEnd = 70000 # [s]
-MaxTimeStepSize = 1e6
+MaxTimeStepSize = 1e5
 
 [Grid]
 UpperRight = 1 1
@@ -15,10 +15,6 @@ EnableInertiaTerms = false
 [Assembly]
 NumericDifference.BaseEpsilon = 1e-8
 
-[Newton]
-MaxSteps = 10
-MaxRelativeShift = 1e-8
-
 [Vtk]
 WriteFaceData = false
 AddVelocity = false