Remove all the code that constructs metadata.pkl file (#61760)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61760
Remove all code that related to metadata.pkl creation including creating metadata.pkl, converting data from extra/mobile_info.json and extra/producer_info.json to metadata.pkl file.
Test Plan:
## Run buck commands:
- `cd` into `fbcode` then `buck build //caffe2/caffe2/fb/init:init`
- `cd` into `fbcode` then `buck build //caffe2/torch/fb/init:init`
- `buck build //xplat/caffe2:torch_mobile_core`
## Export a PyTorch lite/mobile model
- Run: `flow-cli canary users.xcheng16.pytorch_trainer.TestWorkflow --run-as-secure-group ai_mobile_platform --buck-target //fblearner/flow/projects/users/xcheng16:workflow` under `fbcode` on devserver.
- Resulted Model: metadata.pkl no longer exist
{F632063134}
Reviewed By: guangy10
Differential Revision: D29702943
fbshipit-source-id: ec7964f4aa3a8e09ccc20b1a7e2232f85931dd81
