BUG: incorrect dimensions for surfaceTensionForce

- accidentally introduced by 27c62303ad

STYLE: trial use of brace-initialized dimensionSet

- instead of writing

      dimensionedScalar(dimensionSet(1, -2, -2, 0, 0, 0), Zero);

  we can use C++11 brace-initialization to bundle the parameters
  for the dimensionSet construction and simply write

      dimensionedScalar({1, -2, -2, 0, 0, 0}, Zero);

  Note the following is incorrect syntax (extra brackets):

      dimensionedScalar(({1, -2, -2, 0, 0, 0}), Zero);

applications/solvers/multiphase/icoReactingMultiphaseInterFoam/phasesSystem/phaseSystem/phaseSystem.C

@@ -929,7 +929,7 @@ Foam::phaseSystem::surfaceTensionForce() const
             mesh_
         ),
         mesh_,
-        dimensionedScalar(dimForce, Zero)
+        dimensionedScalar({1, -2, -2, 0, 0, 0}, Zero)
     );
 
     auto& stf = tstf.ref();