Remove MPI Support?

[ferrine]

Description

There is MPI support that we do not test, and do not use, should we remove it now? The implementation is not very complicated, but you need to take special care of how you make linker.

mpi_linker = OpWiseCLinker(schedule=mpi_scheduler)
mpi_mode = Mode(linker=mpi_linker)

https://github.com/pymc-devs/pytensor/blob/main/pytensor/tensor/io.py#L108

History reference
Theano/Theano#916
Theano/Theano#935

[ricardoV94]

Yeah I think we can remove it