Upload exported models and Android apps directly to S3 (#5375)

Summary:
This uses the new `use-s3` input from https://github.com/pytorch/test-infra/pull/5668 to upload exported models and Android artifacts directly to S3.  iOS artifacts need to be built on GH runner with Xcode, so they will still need to go through GH before being uploaded to S3.

This helps address scaling issue when upload large files to GitHub, for example:

* Timing out https://github.com/pytorch/executorch/actions/runs/10858058150/job/30136354800
* or just fail in the middle of the upload https://github.com/pytorch/executorch/actions/runs/10856291106/job/30132545832

Pull Request resolved: https://github.com/pytorch/executorch/pull/5375

Reviewed By: kirklandsign

Differential Revision: D62680104

Pulled By: huydhn

fbshipit-source-id: 4f82317526770b49c0ad2a555638ddb5dfa6316b