Do not free resources in `MPI_*_free` calls

Function such as `MPI_Op_free` only decrement a reference counter, they do not actually free the internal MPI objects. These MPI objects may still be in use. Freeing resources or un-root objects in such a call can lead to accessing uninitialized memory.

In my experience, this means that the some of the `MPI_*_free` calls may not actually be able to free anything (e.g. `MPI_Op_free`). Many objects may need to remain allocated indefinitely (or until `MPI_Finalize`).

Start by tracing the MPI_*_free entry points, especially MPI_Op_free, and inspect how their reference counters and internal MPI objects are handled. Check the MPI wrapper behavior against the stated lifetime concern; done means the calls cannot expose uninitialized or prematurely released resources, with relevant validation added where the project supports it.

Written by the indexing model from the issue text.