Use linux runner for Android Device Farm test job (#4177)

Summary:
I should have realized this earlier, but using our Linux runner is more efficient than GitHub runner when it comes to download from and upload large files to S3, i.e. the exported llama model, because the traffic is within AWS data center.

Pull Request resolved: https://github.com/pytorch/executorch/pull/4177

Reviewed By: kirklandsign

Differential Revision: D59509449

Pulled By: huydhn

fbshipit-source-id: 8e6bfd731d297451513721d537e53e3130e755f9