group_from_session_pset - remove confusing error message

The implementation of MPI_Group_from_session_pset was emitting a confusing error message when querying the PMIx server for members of a process group. The routine was using a method for creating an error message that was intended to be using during mpi initialization. Remove that statement and let an error code be returned. Related to #13497 Signed-off-by: Howard Pritchard <howardp@lanl.gov>

Author: hppritcha

ompi/instance/instance.c

@@ -1313,7 +1313,6 @@ static int ompi_instance_group_pmix_pset (ompi_instance_t *instance, const char
  ret = opal_pmix_convert_status(rc);
  break;
  }
- ompi_instance_print_error ("PMIx_Query_info() failed", ret);
  goto fn_w_query;
  }
 
@@ -1334,7 +1333,6 @@ static int ompi_instance_group_pmix_pset (ompi_instance_t *instance, const char
 if (OPAL_SUCCESS == rc) {
  group->grp_proc_pointers[i] = ompi_proc_find_and_add(&pname,&isnew);
  } else {
- ompi_instance_print_error ("OPAL_PMIX_CONVERT_PROCT failed %d", ret);
  ompi_group_free(&group);
  goto fn_w_info;
  }