Increase timeout threshold for on-device benchmarking (#5324)

Summary:
Seeing timeout issue in iOS workflow due to queueing/scheduling. We will increase the timeout threshold to 120mins (from 60mins).

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Pull Request resolved: https://github.com/pytorch/executorch/pull/5324

Reviewed By: huydhn, kirklandsign

Differential Revision: D62621640

Pulled By: guangy10

fbshipit-source-id: 3b6d4a4adca5776c18b466286ddc2da2a21de196