[WOQ][Inductor] Enable CUDA coverage for _weight_int8pack_mm (pytorch#163461)

Summary:
What: Unskip the CUDA path for test_int8_weight_only_quant in test_torchinductor.py as the kernel was added by pytorch#159325.

Why: Confirm CUDA backend for _weight_int8pack_mm is registered.

Test Plan:
```
buck2 test 'fbcode//mode/opt' fbcode//caffe2/test/inductor:test_inductor_cuda
```
https://www.internalfb.com/intern/testinfra/testrun/2533275104869494

Differential Revision: D82926440

Pull Request resolved: pytorch#163461
Approved by: https://github.com/jerryzh168

Author: bbeckca

test/inductor/test_torchinductor.py

@@ -2453,7 +2453,6 @@ def fn(a):
         self.common(fn, [packed])
 
     @xfail_if_mps_unimplemented
-    @skipCUDAIf(True, "No _weight_int8pack_mm implementation on CUDA")
     @skipIfXpu(msg="No _weight_int8pack_mm implementation on XPU")
     def test_int8_weight_only_quant(self):
         def convert_weight_to_int8pack(b):