Handle multi-user case in split-cat simplification (#101473)
Summary: Post refactoring, previous diff had a drop in QPS gained on prod model - because of multi-user getitems. Multi user getitems can be handled by the replacer.
Differential Revision: D45893988
Pull Request resolved: https://github.com/pytorch/pytorch/pull/101473
Approved by: https://github.com/jansel
