Simplify .github/scripts/generate_ci_workflows.py (#58491)
Summary:
This PR simplifies `.github/scripts/generate_ci_workflows.py` by using the same strategy as https://github.com/pytorch/pytorch/issues/54344, representing workflows as plain data to avoid duplicating the definition of the `generate_workflow_file` function. This will make the script easier to maintain if/when that function is modified and/or more workflow types are added.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58491
Test Plan:
The Lint job in CI; specifically:
```
make generate-gha-workflows
mypy --config mypy-strict.ini
```
Reviewed By: malfet, seemethere
Differential Revision: D28511918
Pulled By: samestep
fbshipit-source-id: aaf415a954d938a29aee7c9367c9bc2b9f44bb01
