addressing the reviewing comments for PR OPM/opm-simulators#3039

putting the numerical aquifer related modification in a function and the
function is called after the equilibration calculation, so it will work
for different equilibration methods.

opm/simulators/aquifers/AquiferNumerical.hpp

@@ -60,7 +60,6 @@ public:
     {
         this->cell_to_aquifer_cell_idx_.resize(this->ebos_simulator_.gridView().size(/*codim=*/0), -1);
 
-        // TODO: here, the parallelisation is obviously ignored
         for (size_t idx = 0; idx < aquifer.numCells(); ++idx) {
             const auto& cell = *(aquifer.getCellPrt(idx));
             const int global_idx = cell.global_index;