[release/2.14] Sync test channel CUDA/ROCm arches with what 2.14 builds (#8498)

Follow-up to #8495, which bumped `CURRENT_CANDIDATE_VERSION` to 2.14.0
on this branch but left the arch dicts on their 2.13-era values.

The test channel now serves 2.14.0 release candidates, so its arch lists
must match what `pytorch/pytorch` `release/2.14` actually builds
([`.github/scripts/generate_binary_build_matrix.py`](https://github.com/pytorch/pytorch/blob/release/2.14/.github/scripts/generate_binary_build_matrix.py)):

```python
CUDA_ARCHES = ["12.6", "13.0", "13.2", "13.4"]
ROCM_ARCHES = ["7.2", "7.14"]
```

## Changes

| dict | before | after | why |
| --- | --- | --- | --- |
| `CUDA_ARCHES_DICT["test"]` | `12.6, 13.0, 13.2` | `12.6, 13.0, 13.2,
13.4` | cu134 RC wheels were never validated |
| `ROCM_ARCHES_DICT["test"]` | `7.1, 7.2` | `7.2, 7.14` | `7.1` is not
built for 2.14 — validation looked for wheels that don't exist and
skipped rocm7.14 |
| `PYTHON_ARCHES_DICT["test"]` | — | unchanged | already matches nightly
|

The `release` channel entries are deliberately left alone — they still
describe GA 2.13 and move as part of the 2.14 go-live step.

## Test plan

- `python -m tools.tests.test_generate_binary_build_matrix` — 11 tests
pass.
- `python -m tools.tests.test_generate_binary_build_matrix
--update-reference-files` — no asset changes.
- Generated linux wheel matrix, before -> after:

| channel | `stable_version` | cuda | rocm |
| --- | --- | --- | --- |
| test | 2.14.0 (unchanged) | +`cu134` | `7.1` -> **`7.14`** |
| release | unchanged (2.13.0) | unchanged | unchanged |
| nightly | unchanged | unchanged | unchanged |

#8497 makes the equivalent arch sync on `main`.

Authored with the assistance of Claude Code.

Author: atalman

tools/scripts/generate_binary_build_matrix.py

@@ -45,13 +45,13 @@
 }
 CUDA_ARCHES_DICT = {
     "nightly": ["12.6", "13.0", "13.2", "13.4"],
-    "test": ["12.6", "13.0", "13.2"],
+    "test": ["12.6", "13.0", "13.2", "13.4"],
     "release": ["12.6", "13.0", "13.2"],
 }
 
 ROCM_ARCHES_DICT = {
     "nightly": ["7.2", "7.14"],
-    "test": ["7.1", "7.2"],
+    "test": ["7.2", "7.14"],
     "release": ["7.1", "7.2"],
 }