## Why
`rust-release` cache restore has had very low practical value, while
cache save consistently costs significant time (usually adding ~3
minutes to the critical path of a release workflow).
From successful release-tag runs with cache steps (`289` runs total):
- Alpha tags: cache download averaged ~5s/run, cache upload averaged
~230s/run.
- Stable tags: cache download averaged ~5s/run, cache upload averaged
~227s/run.
- Windows release builds specifically: download ~2s/run vs upload
~169-170s/run.
Hard step-level signal from the same successful release-tag runs:
- Cache restore (`Run actions/cache`): `2,314` steps, total `1,515s`
(~0.65s/step).
- `95.3%` of restore steps finished in `<=1s`; `99.7%` finished in
`<=2s`; `0` steps took `>=10s`.
- Cache save (`Post Run actions/cache`): `2,314` steps, total `66,295s`
(~28.65s/step).
Run-level framing:
- Download total was `<=10s` in `288/289` runs (`99.7%`).
- Upload total was `>=120s` in `285/289` runs (`98.6%`).
The net effect is that release jobs are spending time uploading caches
that are rarely useful for subsequent runs.
## What Changed
- Removed the `actions/cache@v5` step from
`.github/workflows/rust-release.yml`.
- Removed the `actions/cache@v5` step from
`.github/workflows/rust-release-windows.yml`.
- Left build, signing, packaging, and publishing flow unchanged.
## Validation
- Queried historical `rust-release` run/job step timing and compared
cache download vs upload for alpha and stable release tags.
- Spot-checked release logs and observed repeated `Cache not found ...`
followed by `Cache saved ...` patterns.
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