ci: increase Windows release workflow timeouts (#20343)

## Why

#20271 increased the `90`-minute timeout in `rust-release.yml`, but it
did not update the reusable Windows workflow in
`rust-release-windows.yml`. As a result, the Windows release compile
jobs were still capped at `60` minutes and the `windows-x64` primary
build could continue timing out.

We are keeping the existing `90`-minute timeout in `rust-release.yml`.
That increase was still directionally correct because the top-level
release build benefits from extra headroom; the mistake was assuming it
also covered the reusable Windows jobs.

## What Changed
- increase the reusable Windows release workflow timeouts in
`rust-release-windows.yml` from `60` minutes to `90` minutes
- update the comment in `rust-release.yml` so it no longer implies that
the top-level timeout covers the Windows reusable jobs

.github/workflows/rust-release.yml

@@ -49,9 +49,8 @@ jobs:
     needs: tag-check
     name: Build - ${{ matrix.runner }} - ${{ matrix.target }} - ${{ matrix.bundle }}
     runs-on: ${{ matrix.runs_on || matrix.runner }}
-    # Codex binaries can take a long time to build, particularly on Windows.
-    # Ideally, this would be 60 minutes, but let's add some headroom because
-    # having to restart a release build due to a timeout is a major pain.
+    # Release builds can take a long time, so leave some headroom to avoid
+    # having to restart the full workflow due to a timeout.
     timeout-minutes: 90
     permissions:
       contents: read