quant: remove hypothesis and int32 from layernorm test (#37947)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37947
The current test is flaky, removing two potential causes of flakiness.
Test Plan:
CI
Imported from OSS
Differential Revision: D21434861
fbshipit-source-id: 82ea5762f3bb07a12052cde29729d73e95da8ddd
