test(e2e): pin upgrade compatibility to rc.5 and cover bucket configuration (#7217)

test(e2e): prove bucket config survives rc.5 upgrade and rollback

Add two upgrade-compatibility scenarios pinned to the on-demand-migration
series' on-disk surfaces: BucketMetadata's 44 -> 46 msgpack keys, the
fail-closed bucket-config reads of rustfs#7172, the encryption-gated PUT
path of rustfs#7183, and the default-on migration module of rustfs#7089.

The upgrade case writes versioning, SSE-S3 default encryption, a validated
replication target plus rule, lifecycle, tags, quota, a public access block,
a bucket policy and an object lock configuration with the pinned previous
release, then asserts each one reads back unchanged on the current build,
that list-remote-targets still reports the target, that writes to the
encrypted and plain buckets keep their encryption posture, that every
pre-upgrade object including a multipart one is byte-identical, and that an
unconfigured bucket reports no migration and still answers NoSuchKey.

The rollback case is the reverse: the current build writes the 46-key blob
and the previous release must decode it by skipping the two unknown keys.

docs/testing/ci-gates.md

@@ -49,7 +49,7 @@ Promotion rule: never promote a report-only lane to required from one green run.
 | PR touching `paths` in `fuzz.yml` | `Build Fuzz Harness`, `Smoke / <target>` | `fuzz.yml` `fuzz-build`, `pr-fuzz-smoke` | Report-only | `MAX_TOTAL_TIME=60 ./scripts/fuzz/run.sh` |
 | PR touching `paths` in `windows-filesystem.yml` | `Rename Safety` | `windows-filesystem.yml` `rename-safety` | Report-only | the `cargo test -p rustfs-ecstore --lib <filter>` commands in the job, on Windows |
 | PR touching `paths` in `coverage.yml` | `Workspace line coverage` | `coverage.yml` `coverage` | Report-only | `make coverage`; `python3 scripts/check_security_coverage.py target/llvm-cov/coverage.json` |
-| PR touching `paths` in `e2e-upgrade.yml` | `Direct upgrade from rc.2` | `e2e-upgrade.yml` `direct-upgrade` | Report-only | the `cargo test --locked -p e2e_test` command in the job with `RUSTFS_UPGRADE_SOURCE_BINARY` pointing at the pinned previous release |
+| PR touching `paths` in `e2e-upgrade.yml` | `Direct upgrade from the previous release`, `Mixed-version rolling upgrade from the previous release`, `Bucket configuration survives the upgrade`, `Rollback reads current bucket metadata` | `e2e-upgrade.yml` `upgrade` matrix | Report-only | the `cargo test --locked -p e2e_test` command in the job with `RUSTFS_UPGRADE_SOURCE_BINARY` pointing at the pinned previous release (`UPGRADE_SOURCE_VERSION`) |
 | PR touching `paths` in `oidc-keycloak.yml` | `OIDC Keycloak live gate` | `oidc-keycloak.yml` `oidc-keycloak-live` | Report-only | `cargo build --locked -p rustfs --bin rustfs`, then `bash scripts/test/oidc_keycloak_live.sh ./target/debug/rustfs` |
 | PR touching `paths` in `targets-integration.yml` | `PostgreSQL, MySQL, AMQP, and NATS` | `targets-integration.yml` `targets-live` | Report-only | start the containers as in the job, export the `RUSTFS_TEST_*` DSNs, then the job's `cargo test --locked -p rustfs-targets --test <name> -- --ignored --test-threads=1` commands |
 | PR limited to main-CI-excluded paths | `Quick Checks`, `Test and Lint` | `ci-docs-only.yml` `quick-checks`, `test-and-lint` | Required | `git diff --check`; `make doc-paths-check`; `scripts/check_no_planning_docs.sh` |
@@ -84,7 +84,7 @@ Scheduled lanes never block a PR. Their workflow-local gate fails the run, sched
 | `mint.yml` (weekly) | `mint` | report-only by design; per-suite PASS/FAIL/NA and raw `log.json` | yes | pinned Docker sequence in the workflow |
 | `coverage.yml` (weekly) | `coverage` | report-only trend; lcov and JSON artifact | yes | `make coverage` |
 | `runner-hygiene.yml` (monthly) | `check-ephemerality` | runner ephemerality | yes | dispatch |
-| `e2e-upgrade.yml` (weekly) | `direct-upgrade` | upgrade gate; server logs | no | see the PR row |
+| `e2e-upgrade.yml` (weekly) | `upgrade` (4-case matrix) | upgrade and rollback gate; server logs | no | see the PR row |
 | `oidc-keycloak.yml` (weekly) | `oidc-keycloak-live` | live OIDC gate | no | see the PR row |
 | `targets-integration.yml` (nightly) | `targets-live` | live target gate; container logs | no | see the PR row |
 | `scheduled-validation-freshness.yml` (nightly) | `check-freshness` | fails on a never-created or stale schedule | n/a | dispatch |