remove clone ops pass (#4058)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/4058

In the Vulkan backend, we always create copies when running an op, so the clone op is effectively a no-op with extra memory read/writes.
Adding a pass to strip out clone ops.

Reviewed By: copyrightly

Differential Revision: D58761417

fbshipit-source-id: 1d9a1cdd295626cda8e4308b45ae6a6c2502b079