Fix mesh in a test

[kronbichler]

It turned out that the mesh created by hyper_shell when the boundary cells are curved by

dealii/include/deal.II/grid/grid_generator.h

Lines 749 to 752 in c8d3544

	hyper_ball(Triangulation<dim> &tria,
	const Point<dim> &center = Point<dim>(),
	const double radius = 1.,
	const bool attach_spherical_manifold_on_boundary_cells = false);

upon refinement some invalid transformations are generated for some mappings (MappingQ(2) in this example). We should not do that. Found by looking at #16317.

[peterrum]

Thanks!

[peterrum]

@kronbichler The serial tester is not passing.

[kronbichler]

Indeed, I forgot that the text outputs actual numbers of the mesh. (Which is funny given that I spent quite some time to understand the test and the issue in the other PR.)