[Quant] Respect non_leaf_module_list for activation modules (#88498)
Summary: This commit fixes the bug where `non_leaf_module_list`
was not respected for activation modules like `torch.nn.Sigmoid`
and `torch.nn.Tanh`. Today, these modules default to
`default_fixed_qparams_range_0to1_fake_quant`, and there is no
way to configure them to use any other activation_post_process
(e.g. FixedQParamsObserver) (see this [mapping](https://github.com/pytorch/pytorch/blob/dc00bb51b8d370bf3891f0edb2c6e0c2914e329a/torch/ao/quantization/quantization_mappings.py#L188-L193)).
`non_leaf_module_list` is a "list of non-leaf modules we want
to add observer" (see prepare docstring). If the user explicitly
specified to insert observers for these modules, we should respect
that instead of continuing to use the default.
Test Plan:
python test/test_quantization.py TestQuantizeEagerPTQStatic.test_activations_in_non_leaf_module_list
Reviewers: vkuzo, jerryzh168
Subscribers: vkuzo, jerryzh168
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88498
Approved by: https://github.com/jerryzh168
