[T/GWF] Rename update expected solution.

- Rename to better reflect the contained date.
- Expected solution update due to output of specific flux instead of flux.

ProcessLib/GroundwaterFlow/Tests.cmake

@@ -319,7 +319,7 @@ AddTest(
     TESTER vtkdiff
     REQUIREMENTS NOT OGS_USE_MPI
     DIFF_DATA
-    wedge_1x1x1_1e3_prism_complete_surface.vtu wedge_1x1x1_1e3_prism_complete_surface_surfaceflux_t_1.000000.vtu surfaceflux_reference surfaceflux 1e-15 1e-15
+    wedge_1x1x1_1e3_prism_complete_surface_specific_flux_t_1.000000.vtu wedge_1x1x1_1e3_prism_complete_surface_specific_flux_t_1.000000.vtu specific_flux specific_flux 1e-15 1e-15
 )
 
 # SQUARE 1x1 GROUNDWATER FLOW TEST -- AXIALLY SYMMETRIC

Tests/Data/Elliptic/wedge_1x1x1_GroundWaterFlow/wedge_1e3_prism_surfaceflux_diagonal.prj

@@ -20,8 +20,8 @@
             </secondary_variables>
             <calculatesurfaceflux>
                 <mesh>wedge_1x1x1_1e3_prism_complete_surface</mesh>
-                <property_name>surfaceflux</property_name>
-                <output_mesh>wedge_1x1x1_1e3_prism_complete_surface_surfaceflux.vtu</output_mesh>
+                <property_name>specific_flux</property_name>
+                <output_mesh>wedge_1x1x1_1e3_prism_complete_surface_specific_flux.vtu</output_mesh>
             </calculatesurfaceflux>
         </process>
     </processes>