Add failing test for multiple ranks and threads

[jh66637]

@kronbichler @peterrum

MatrixFree::reinit() fails with multiple ranks and threading enabled. I traced this down to the update of values on inner faces. The error reads

An error occurred in line <1005> of file </home/johannes/workspace/dealii/include/deal.II/lac/dynamic_sparsity_pattern.h> in function
    void dealii::DynamicSparsityPattern::add(dealii::DynamicSparsityPattern::size_type, dealii::DynamicSparsityPattern::size_type)
The violated condition was: 
    ::dealii::deal_II_exceptions::internals::compare_less_than(i, n_rows())
Additional information: 
    Index 16 is not in the half-open range [0,16).

Using only one thread (Utilities::MPI::MPI_InitFinalize mpi_init(argc, argv, 1)) works as expected. Running with one rank and threading enabled works as well.

[kronbichler]

This is a good test. I checked #16340 with it. I would suggest to run it only with 2 MPI rank because I think that exposes the bug already. We should try not to use more resources than necessary, because we do MPI + threads, causing a lot of load on the tester.

[kronbichler]

Does the 3D test need to be such big? I would hope that 2 refinements and a polynomial degree 2 should suffice (the 2D variant is ok).

[kronbichler]

You need to run the indent script on this test.

[kronbichler]

I suggest waiting with merging this test until #16340 is merged, to be sure things are fine.

[jh66637]

This is fine for me. Thank you for the quick fix :)

[kronbichler]

/rebuild

[kronbichler]

Could you please rebase this PR to pass the test?