test(e2e): add 4-node upgrade coverage for history and IAM

Seed a 4-node cluster on the pinned previous release, then prove
direct and rolling upgrades keep historical objects and IAM AK/SK
working. The distributed Actions lane now downloads that binary.

Co-authored-by: RustFS <hello@rustfs.com>

.github/workflows/e2e-distributed.yml

@@ -16,10 +16,11 @@
 #
 # Each selected test starts a real localhost cluster via
 # `RustFSTestClusterEnvironment` (4 processes; 4 drives per node unless the
-# case is a two-site 4-node 1-drive pair). Membership is
+# case is a two-site 4-node 1-drive pair or a 4-node upgrade). Membership is
 # `[profile.e2e-distributed]` in `.config/nextest.toml`. This is not a required
 # merge check: it is the scheduled/dispatch counterpart to the hardware
 # functional chain that currently clones rustfs/auto-testing onto three VMs.
+# Upgrade cases download the same pinned previous release as e2e-upgrade.yml.
 
 name: e2e-distributed
 
@@ -51,6 +52,10 @@ jobs:
       NO_PROXY: 127.0.0.1,localhost
       HTTP_PROXY: ""
       HTTPS_PROXY: ""
+      # Pinned previous release used by distributed::upgrade_test (same pin as e2e-upgrade.yml).
+      UPGRADE_SOURCE_VERSION: 1.0.0-rc.2
+      UPGRADE_SOURCE_ASSET: rustfs-linux-x86_64-gnu-v1.0.0-rc.2.zip
+      UPGRADE_SOURCE_SHA256: 7c789386bf85278f865b8e0d359bf4edb84d5aa408cc3fa54a18c25ca74cd6e7
     steps:
       - name: Checkout repository
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
@@ -65,6 +70,21 @@ jobs:
           cache-save-if: ${{ github.ref == 'refs/heads/main' }}
           install-build-packaging-tools: 'false'
 
+      - name: Download pinned previous release
+        env:
+          SOURCE_DIR: ${{ runner.temp }}/rustfs-upgrade-source
+        run: |
+          set -euo pipefail
+          mkdir -p "$SOURCE_DIR"
+          archive="$SOURCE_DIR/$UPGRADE_SOURCE_ASSET"
+          curl --fail --location --retry 3 --output "$archive" \
+            "https://github.com/${GITHUB_REPOSITORY}/releases/download/${UPGRADE_SOURCE_VERSION}/${UPGRADE_SOURCE_ASSET}"
+          echo "$UPGRADE_SOURCE_SHA256  $archive" | sha256sum --check --strict
+          unzip -q "$archive" -d "$SOURCE_DIR"
+          chmod +x "$SOURCE_DIR/rustfs"
+          test -x "$SOURCE_DIR/rustfs"
+          echo "RUSTFS_UPGRADE_SOURCE_BINARY=$SOURCE_DIR/rustfs" >> "$GITHUB_ENV"
+
       - name: Build rustfs binary
         run: |
           cargo build -p rustfs --bins