Remove or consolidate 57 test cases that cannot catch regressions
(literal-constant asserts, construct-then-assert, derived-serde
round-trips, near-duplicate env/getter matrices) in common, config,
iam, madmin, and object-capacity, keeping all wire-format and
error-path guards. Add 13 tests for previously uncovered high-risk
behavior: filemeta version-sort determinism and merge resilience to
garbage headers, zip extraction path-traversal rejection and exact
limit boundaries, JWT tampered-signature rejection, and the bytes
variant of dual-key (rustfs/minio) metadata fallback and precedence.
Test-only change; no production code touched.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>