ci(s3-tests): pin upstream suite, add weekly full sweep and compat report (#4204)

Reworks the S3 compatibility test harness for reproducibility and faster
feedback:

- Pin ceph/s3-tests to a fixed commit (S3TESTS_REV, fetch-by-SHA) so the
  449-test PR gate is reproducible; previously every run cloned upstream
  master, letting test renames or assertion changes break CI silently.
- PR gate (ci.yml s3-implemented-tests): MAXFAIL=0 + XDIST=4 so a single
  CI round reports every failure in parallel instead of stopping at the
  first one serially.
- Add TEST_SCOPE=all to run.sh to run the entire upstream suite, and
  report_compat.py to diff junit results against the classification
  lists (regressions, promotion candidates, unclassified tests).
- Rewrite e2e-s3tests.yml: delegate execution to run.sh (single source
  of truth; also fixes the broken config generation that left S3_PORT
  empty), add a weekly scheduled full sweep that fails only on whitelist
  regressions, and fix the multi-node topology to a real distributed
  cluster (endpoint-style RUSTFS_VOLUMES) instead of four independent
  single-node stores behind a load balancer.
- Docs: rewrite stale .github/s3tests/README.md (marker-era strategy),
  update scripts/s3-tests/README.md, fix dead build_testexpr.sh
  reference in S3_COMPAT_WORKFLOW.md, drop legacy non_standard_tests.txt.

All 747 classified test names verified present at the pinned revision;
13 upstream tests are currently unclassified and will surface in the
first full-sweep report.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -429,7 +429,8 @@ jobs:
           DEPLOY_MODE=binary \
           RUSTFS_BINARY=./target/debug/rustfs \
           TEST_MODE=single \
-          MAXFAIL=1 \
+          MAXFAIL=0 \
+          XDIST=4 \
           S3_PORT="${S3_PORT}" \
           DATA_ROOT="${RUN_ROOT}" \
           S3TESTS_CONF=artifacts/s3tests-single/s3tests.conf \