ns for fx: remove torch.ops.quantized.cat
Summary:
FX graph mode quantization no longer uses `torch.ops.quantized.cat`,
instead `torch.cat` can use quantized inputs.
This PR removes the outdated mapping from NS for FX.
Test plan:
```
python test/test_quantization.py -k FXNumericSuite
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76988
Approved by: https://github.com/jerryzh168
