ci: stop archiving every dependency's unpacked source in each cache (#5566)

The four consolidated ci keys plus the build keys still do not fit the
repository's fixed 10GB Actions cache quota, so LRU keeps evicting them:
measured demand is ci-dev 2331MB + ci-feat-proto 2310MB + ci-feat-rio 1951MB +
ci-uring 1317MB + two build legs at ~1429MB + cargo-deny 844MB, and main pushes
add two more build legs. That is roughly 14.4GB against 10.24GB. The symptom is
misleading: Cache Warm reports every job successful and the restores log "full
match: true", yet ci-feat-rio and ci-uring disappear from the cache list between
runs.

cache-all-crates was the wrong default for this repository. With it set to true,
rust-cache's cleanup returns before pruning ~/.cargo/registry/src and its config
archives the whole registry, so every cache carried the unpacked source tree of
every dependency — not, as the name suggests, just a few extra crates.

Setting it to false is rust-cache's own default and loses no coverage: the
package set comes from `cargo metadata --all-features`, a strict superset of any
single lane's feature closure; -sys crates are explicitly exempt from pruning,
since their source timestamps would otherwise trigger rebuilds; and everything
pruned is re-unpacked from the .crate files still in registry/cache, whose
mtimes crates.io normalises, so cargo fingerprints stay valid.

Applied to the setup composite and to audit.yml's own rust-cache. Cache Warm
now also reports the sizes of registry/src, registry/cache, registry/index,
~/.cargo/git and target/ to the step summary, immediately before rust-cache's
post step archives them, so the size of the effect is measured rather than
assumed.

The new sizes only appear once the cache key next rotates, since rust-cache
skips the save entirely on an exact key hit. Deliberately not forcing that by
bumping prefix-key: it would invalidate every family at once and produce a
repository-wide cold build.

Refs: rustfs/backlog#1598, rustfs/backlog#1600

.github/actions/setup/action.yml

@@ -111,7 +111,18 @@ runs:
     - name: Setup Rust cache
       uses: Swatinem/rust-cache@e18b497796c12c097a38f9edb9d0641fb99eee32 # v2
       with:
-        cache-all-crates: true
+        # false is rust-cache's own default. With true, cleanup.ts returns
+        # *before* pruning ~/.cargo/registry/src, and config.ts archives the
+        # whole registry — so every cache carried the unpacked source tree of
+        # every dependency, not just "a few extra crates".
+        #
+        # No coverage is lost: getPackages runs `cargo metadata --all-features`,
+        # a strict superset of any single lane's feature closure, and -sys crates
+        # are explicitly exempted from pruning (their src timestamps would
+        # otherwise trigger rebuilds). Anything pruned is re-unpacked from the
+        # .crate files still in registry/cache, whose mtimes crates.io
+        # normalises, so cargo fingerprints stay valid.
+        cache-all-crates: false
         cache-on-failure: true
         shared-key: ${{ inputs.cache-shared-key }}
         save-if: ${{ inputs.cache-save-if }}