ns for fx: remove GroupNorm from mapping
Summary:
GroupNorm quantization is defined but it looks like FX graph
mode quantization does not have it enabled.
Removing it from NS for FX.
Test plan:
```
python test/test_quantization.py -k FXGraphMatcher
python test/test_quantization.py -k FXNumericSuite
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76991
Approved by: https://github.com/jerryzh168
