coll_ftagree_earlyreturning.c: temporarily remove dead code

being deleted because, per discussion between @bosilca and @jsquyres
on 29 Apr 2021, @bosilca is pretty sure that this code *should* be
being invoked from somewhere -- otherwise, we likely have a leak in
MPI_FINALIZE.  His team is looking into it.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>