Scatterer from DOLFINx #3885 gives different results than prior implementation

Breaks `distribute_ghost_data`.
To be investigated.
Probably `std::int8_t` related. PR in question: https://github.com/FEniCS/dolfinx/pull/3855
New code looks like:
```c++
MPI_Request request = MPI_REQUEST_NULL;
ghost_scatterer.scatter_fwd_begin(indicator.data(),
recieve_indicator.data(), request);
ghost_scatterer.scatter_end(request);
```
old code was
```c++
ghost_scatterer.scatter_fwd(std::span(indicator),
std::span(recieve_indicator));
```