Build the Linux wheels on OSDC runners (pytorch#22753)

Takes all four Linux wheel workflows off EC2.

One input on the matrix generator. pytorch/test-infra#8789 adds
`runner-fleet`, which maps each row's `validation_runner` to its ARC
equivalent — release-isolated on the refs these workflows publish from,
regular otherwise, so PR builds move off EC2 too.

| arch | rows | regular | release |
| --- | --- | --- | --- |
| x86_64 | cpu | `mt-l-x86iavx512-8-64` | `mt-rel-l-x86iavx512-44-340` |
| x86_64 | cuda | `mt-l-x86aavx2-29-113-a10g` |
`mt-rel-l-x86aavx2-29-113-l4` |
| aarch64 | any | `mt-l-arm64g4-16-62` | `mt-rel-l-arm64g3-44-340` |

The cuda x86_64 rows keep a device, which they need:
`test_cuda_linux.py` exports a model through the CUDA partitioner and
runs it against eager, and on a CPU runner that check would skip rather
than fail.

Depends on pytorch/test-infra#8789.

Authored with Claude Code.

Author: huydhn

.github/workflows/build-wheels-aarch64-linux.yml

@@ -41,6 +41,7 @@ jobs:
       os: linux-aarch64
       test-infra-repository: pytorch/test-infra
       test-infra-ref: main
+      runner-fleet: osdc
       with-cuda: disabled
       with-rocm: disabled
       python-versions: '["3.10", "3.11", "3.12", "3.13", "3.14"]'

.github/workflows/build-wheels-cuda-aarch64-linux.yml

@@ -45,6 +45,7 @@ jobs:
       os: linux-aarch64
       test-infra-repository: pytorch/test-infra
       test-infra-ref: main
+      runner-fleet: osdc
       with-cuda: enable
       with-cpu: disable
       with-rocm: disable

.github/workflows/build-wheels-cuda-linux.yml

@@ -45,6 +45,7 @@ jobs:
       os: linux
       test-infra-repository: pytorch/test-infra
       test-infra-ref: main
+      runner-fleet: osdc
       with-cuda: enable
       with-cpu: disable
       with-rocm: disable

.github/workflows/build-wheels-linux.yml

@@ -41,6 +41,7 @@ jobs:
       os: linux
       test-infra-repository: pytorch/test-infra
       test-infra-ref: main
+      runner-fleet: osdc
       with-cuda: disabled
       with-rocm: disabled
       python-versions: '["3.10", "3.11", "3.12", "3.13", "3.14"]'