refactor(storage): resolve staged dead code in store module (#5283)

refactor(storage): resolve staged dead code in store module (#730)

Drop the store module's blanket #![allow(dead_code)] and resolve every
unit it was masking, instead of keeping them staged:

- write_persistent_key_only_index: the keys-only writer wrapper only had
  test callers; the in-process rebuild flow already exists and uses the
  _with_metadata variant (prepare -> rebuild, triggered lazily from the
  opt-in listing path). Tests call _with_metadata directly now.
- ListIndexLifecycle::recover_after_restart / mark_corrupt: production
  derives index health per request from the persisted artifacts (index
  file + namespace mutation journal), and restart recovery already lives
  in load_persistent_key_only_index's journal restore. The persisted-
  lifecycle design these transitions served was superseded, and Corrupt
  had no detector, so the never-constructed Corrupt state/reason
  variants go with them.
- record_list_objects_index_opt_in_fallback (+ helpers): superseded by
  the inline per-site fallback recording in the opt-in listing path; the
  recorder recomputed health with a hardcoded None provider, so it could
  only ever report a disabled-based reason.
- Provider-contract traits (Generation/Page/PageIterator/KeyLookup):
  provider dispatch went the ListObjectsIndexProviderKind enum route;
  only ListMetadataIndexHealth is live (dyn in source-mode selection)
  and stays, minus its unused is_healthy default.
- Delete the unused list_quorum_from_env/RUSTFS_API_LIST_QUORUM pair,
  fold should_resume_local_decommission and
  should_auto_start_rebalance_after_recovered_meta into their surviving
  primitives, drop get_disk_via_endpoint, and cfg(test) the remaining
  test-only conveniences.

crates/ecstore/src/store/mod.rs

@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// #730: store startup/listing helpers are staged while global state is moved to owners.
-#![allow(dead_code)]
 #![allow(clippy::map_entry)]
 
 use crate::bucket::lifecycle::bucket_lifecycle_audit::LcEventSrc;