Move generated keyword out of gen_mobile_upgraders.py (#71938)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71938
`generated` will trigger the generated changes and hide the file changes. It's also misleading, because `gen_mobile_upgraders.py` itself is not autogen. Separate the keyword out from `gen_mobile_upgraders.py` so it's easier to see the changes from `gen_mobile_upgraders.py`.
ghstack-source-id: 147957825
Test Plan:
```
buck run mode/opt //caffe2/torch/fb/mobile/upgrader_codegen:upgrader_codegen
```
Reviewed By: tugsbayasgalan
Differential Revision: D33826982
fbshipit-source-id: 593c19f8ef4c9da776b11650863dc43c0b171cd5
(cherry picked from commit 43038d5bc7a41312a005d62f432c5ca19ed79f21)
