[cleanup][tests] Use new standard grid creator for zeroeq2c

* Use input file for structured grids instead of dgf files for
  zeroeq2c tests

test/freeflow/zeroeq2c/grids/testpipe.dgf

-DGF
-Interval
-0 0 % first corner
-3 1 % second corner
-30 20 % cells in x and y direction
-#
-
-Cube
-0 1 2 3
-#
-
-BOUNDARYDOMAIN
-default 1 % all boundaries have id 1
-#BOUNDARYDOMAIN
-# unitcube.dgf
\ No newline at end of file

test/freeflow/zeroeq2c/test_zeroeq2c.input

@@ -3,7 +3,9 @@ DtInitial = .1 # [s]
 TEnd = 10 # [s]
 
 [Grid]
-File = grids/testpipe.dgf
+LowerLeft = 0 0
+UpperRight = 3 1
+Cells = 30 20
 
 [Problem]
 OutputName = "zeroeq2c"

test/freeflow/zeroeq2c/zeroeq2ctestproblem.hh

@@ -23,12 +23,6 @@
 #ifndef DUMUX_ZEROEQTWOCTESTPROBLEM_HH
 #define DUMUX_ZEROEQTWOCTESTPROBLEM_HH
 
-#if HAVE_UG
-#include <dune/grid/io/file/dgfparser/dgfug.hh>
-#else
-#include <dune/grid/io/file/dgfparser/dgfyasp.hh>
-#endif
-
 #include <dumux/material/fluidsystems/h2oair.hh>
 #include <dumux/material/fluidsystems/gasphase.hh>