Add torch to cloudflare r2 (#7914)

All packages are now by default using r2:
```
PT_R2_PACKAGES_PROD = {
    "torch",
    "torchaudio",
    "torchvision",
    "fbgemm_gpu",
    "fbgemm_gpu_genai",
    "triton",
    "triton_rocm",
    "triton_xpu",
    "pytorch_triton",
    "pytorch_triton_rocm",
    "pytorch_triton_xpu",
}
```

Author: atalman

s3_management/manage_v2.py

@@ -454,6 +454,7 @@
 # These packages will have their URLs point to R2 instead of S3/CloudFront
 # when the path is NOT whl/test and NOT whl/nightly (i.e., prod)
 PT_R2_PACKAGES_PROD = {
+    "torch",
     "torchaudio",
     "torchvision",
     "fbgemm_gpu",