onnxruntime

LayerNorm test fix (#13840)

### Description
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Testcases of LayerNorm with fp16/bf16 are failed in Andriod and IOS
since the two platforms don't support the combinations of datatypes as
well.


https://dev.azure.com/onnxruntime/onnxruntime/_build?definitionId=134&_a=summary

https://dev.azure.com/onnxruntime/onnxruntime/_build?definitionId=53&_a=summary

### Motivation and Context
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- If it fixes an open issue, please link to the issue here. -->