speed up hardswish and hardsigmoid tests (#38256)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38256
Removes hypothesis to speed these tests up, as these tests were flagged as top slow
tests in CI. At the same time, combines the fbgemm and qnnpack test
cases together for better reuse.
Test Plan:
```
python test/test_quantization.py TestQuantizedOps.test_hardswish
python test/test_quantization.py TestQuantizedOps.test_qhardsigmoid
```
Imported from OSS
Differential Revision: D21506831
fbshipit-source-id: 9ff70e4ec7ae30b6948fe808878f0187e631f4d8
