Remove deepcopy (#2502)

Summary:
Add fake program to remove deepcopy.
See: D54826270

Peak memory usage: 38.7 GiB, down from 45GiB.
https://lookaside.facebook.com/intern/diff/file/data/?number=1470390332&download=1

Pull Request resolved: https://github.com/pytorch/executorch/pull/2502

Test Plan:
Imported from GitHub, without a `Test Plan:` line.
```
memray run -m examples.models.llama2.export_llama -c ../llama-models/llama7b/consolidated.00.pth -p ../llama-models/llama7b/config.json -kv --use_sdpa_with_kv_cache -d fp32 --pt2e_quantize "xnnpack_dynamic"
```

```
buck2 run fbcode//executorch/exir/program/test:test_program
```

Reviewed By: cccclai

Differential Revision: D55047794

Pulled By: lucylq

fbshipit-source-id: b2834c05681f4b9d0ea30b92376678e9f3d36736