Use Depot Windows runners for cargo test (#18754)

From 6m 15s -> 3m 54s (total runtime)

See also https://github.com/astral-sh/uv/pull/14122 

We don't use a Dev Drive here so this is trivial (ref #15664)

.github/workflows/ci.yaml

@@ -313,7 +313,7 @@ jobs:
 
   cargo-test-windows:
     name: "cargo test (windows)"
-    runs-on: github-windows-2025-x86_64-16
+    runs-on: depot-windows-2022-16
     needs: determine_changes
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 20