[operators] fix OswaldInterpolationOperator ctor usage

dune/gdt/test/operators/oswald-interpolation.hh

@@ -104,8 +104,8 @@ struct OswaldInterpolationOperatorOnLeafViewTest : public ::testing::Test
   void fulfills_l2_interpolation_estimate()
   {
     auto& self = *this;
-    OswaldInterpolationOperator<GV> oswald_interpolation(
-        self.grid_provider->leaf_view(), *self.space, *self.space, *self.boundary_info);
+    OswaldInterpolationOperator<GV> oswald_interpolation{
+        self.grid_provider->leaf_view(), *self.space, *self.boundary_info};
     oswald_interpolation.assemble();
     auto range = make_discrete_function<V>(*self.space);
     oswald_interpolation.apply(*self.source, range);
@@ -226,8 +226,8 @@ struct OswaldInterpolationOperatorOnLeafViewTest : public ::testing::Test
   void fulfills_h1_interpolation_estimate()
   {
     auto& self = *this;
-    OswaldInterpolationOperator<GV> oswald_interpolation(
-        self.grid_provider->leaf_view(), *self.space, *self.space, *self.boundary_info);
+    OswaldInterpolationOperator<GV> oswald_interpolation{
+        self.grid_provider->leaf_view(), *self.space, *self.boundary_info};
     oswald_interpolation.assemble();
     auto range = make_discrete_function<V>(*self.space);
     oswald_interpolation.apply(*self.source, range);
@@ -402,8 +402,8 @@ struct OswaldInterpolationOperatorOnCubicLeafViewTest : public OswaldInterpolati
   void applies_correctly_on_cubic_grids()
   {
     auto& self = *this;
-    OswaldInterpolationOperator<GV> oswald_interpolation(
-        self.grid_provider->leaf_view(), *self.space, *self.space, *self.boundary_info);
+    OswaldInterpolationOperator<GV> oswald_interpolation{
+        self.grid_provider->leaf_view(), *self.space, *self.boundary_info};
     oswald_interpolation.assemble();
     auto range = make_discrete_function<V>(*self.space);
     oswald_interpolation.apply(*self.source, range);