Merge order-dependent exir/dialects/backend/test (#3700)

Summary:
If we run `test_backend_ops_equivalent_pattern` first, and then `test_backend_ops_with_no_kernel_raise_exception`, it won't raise because the first one has global side effect.

Pull Request resolved: https://github.com/pytorch/executorch/pull/3700

Reviewed By: larryliu0820

Differential Revision: D57647224

Pulled By: kirklandsign

fbshipit-source-id: abbb9a97653271a9435d4fd5c19913b11e151351