[Export] remove unused flags in export (#106336)
Remove unused flags from export_dynamo_config:
Among them:
- capture_scalar_outputs: bool = True. **True by default** in dynamo.export:
- capture_dynamic_output_shape_ops: bool = True. **True by default** in dynamo.export
- specialize_int: bool = True: **True by default** in dynamo.export.
- guard_nn_modules: bool = True: this flag is **not being used** as we never look at nn module guards and assume modules are forzen. See the [doc](https://github.com/pytorch/pytorch/blob/main/torch/_dynamo/config.py#L77) of this flag.
- dynamic_shapes: bool = True: **deprecated by dynamo**: [here](https://github.com/pytorch/pytorch/blob/main/torch/_dynamo/config.py#L55 )
test plan:
Added new test for allow_rnn to test its effectiveness.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106336
Approved by: https://github.com/tugsbayasgalan
