test(ecstore): add shared MockWarmBackend test utility for lifecycle and tier tests (#4716)

* test(ecstore): extract shared MockWarmBackend into a test-util feature (backlog#1148 ilm-6)

The tier/lifecycle integration tests carried two byte-for-byte copies of an
in-memory WarmBackend mock — one in crates/scanner/tests and one in
rustfs/src/app — plus duplicated register_mock_tier and polling helpers. Both
implemented the same ecstore WarmBackend trait.

Consolidate them into ecstore behind a new `test-util` feature, exposed via the
`rustfs_ecstore::api::tier::test_util` facade:

- MockWarmBackend: in-memory WarmBackend with an operation log (for ordering
  assertions such as "local delete precedes remote remove") and fault injection
  (FaultConfig): unreachable, HTTP 5xx, credential rejection, injected latency,
  plus external_remove to simulate an out-of-band remote deletion.
- register_mock_tier / register_mock_tier_backend: register the mock into any
  TierConfigMgr handle (the global manager used by scanner tests or a
  per-instance one used by the app tests).
- xl.meta transition assertion helpers: read_transition_meta,
  assert_transition_meta_consistent (cross-shard consistency of the
  status/tier/remote-key/remote-version-id tuple plus free-version count), and
  free_version_count.
- polling helpers: wait_for_remote_absence, wait_for_object_count,
  wait_for_free_version_absence.

Both existing copies now consume this single definition; `rg 'struct
MockWarmBackend'` collapses to one. The feature is enabled only from
[dev-dependencies], so it never links into the production binary (resolver 3).

Designed for downstream ilm-8 (restore lifecycle) and ilm-11 (tier fault
injection matrix). Coordinates with #4706 (ilm-2), which adds op-logging to the
scanner mock — that op-logging is now part of this shared surface, so #4706
should rebase onto it.

Refs rustfs/backlog#1148 (ilm-6), rustfs/backlog#1155.

* test(ecstore): fix shared MockWarmBackend usage after main merge

- Access stored objects via MockWarmBackend::contains() instead of the now
  private inner objects map (fixes E0609 after the shared test-util refactor).
- Drop dead ReadCloser/ReaderImpl/DiskAPI imports and the unused
  transition_api test re-exports the mock extraction left behind.
- Reword the scanner/rustfs test-util dependency comments so they no longer
  embed the literal rustfs_ecstore:: path that trips the ECStore
  architecture-migration guard.

crates/scanner/tests/storage_api/mod.rs

@@ -23,15 +23,17 @@ pub(crate) use rustfs_ecstore::api::bucket::metadata_sys::{
 };
 pub(crate) use rustfs_ecstore::api::bucket::versioning_sys::BucketVersioningSys;
 pub(crate) use rustfs_ecstore::api::capacity::path2_bucket_object_with_base_path;
-pub(crate) use rustfs_ecstore::api::client::transition_api::{ReadCloser, ReaderImpl};
-pub(crate) use rustfs_ecstore::api::disk::{DiskAPI, DiskOption, STORAGE_FORMAT_FILE, endpoint::Endpoint, new_disk};
+pub(crate) use rustfs_ecstore::api::disk::{DiskOption, STORAGE_FORMAT_FILE, endpoint::Endpoint, new_disk};
 pub(crate) use rustfs_ecstore::api::error::{Error as EcstoreError, is_err_object_not_found, is_err_version_not_found};
 pub(crate) use rustfs_ecstore::api::layout::{EndpointServerPools, Endpoints, PoolEndpoints};
 pub(crate) use rustfs_ecstore::api::runtime::global_tier_config_mgr as get_global_tier_config_mgr;
 pub(crate) use rustfs_ecstore::api::storage::{ECStore, init_local_disks};
-pub(crate) use rustfs_ecstore::api::tier::tier_config::{TierConfig, TierMinIO, TierType};
-pub(crate) use rustfs_ecstore::api::tier::warm_backend::{
-    WarmBackend as ScannerWarmBackend, WarmBackendGetOpts, build_transition_put_options,
+// Shared lifecycle/tier test utilities (rustfs/backlog#1148 ilm-6). The mock
+// backend and xl.meta assertion helpers now live in ecstore behind the
+// `test-util` feature instead of being copied into this crate.
+pub(crate) use rustfs_ecstore::api::tier::test_util::{
+    MockWarmBackend, assert_transition_meta_consistent, free_version_count, register_mock_tier as register_mock_tier_util,
+    wait_for_free_version_absence,
 };
 use rustfs_storage_api as storage_contracts;
 
@@ -42,11 +44,11 @@ pub(crate) mod lifecycle {
     };
 
     pub(crate) use super::{
-        BUCKET_LIFECYCLE_CONFIG, BucketVersioningSys, DiskAPI, DiskOption, ECStore, EcstoreError, Endpoint, EndpointServerPools,
-        Endpoints, IlmAction, LcEvent, LcEventSrc, PoolEndpoints, ReadCloser, ReaderImpl, STORAGE_FORMAT_FILE,
-        ScannerWarmBackend, TierConfig, TierMinIO, TierType, TransitionOptions, WarmBackendGetOpts, build_transition_put_options,
-        enqueue_transition_for_existing_objects, expire_transitioned_object, get_bucket_metadata, get_global_tier_config_mgr,
-        init_background_expiry, init_bucket_metadata_sys, init_local_disks, is_err_object_not_found, is_err_version_not_found,
-        new_disk, path2_bucket_object_with_base_path, update_bucket_metadata,
+        BUCKET_LIFECYCLE_CONFIG, BucketVersioningSys, DiskOption, ECStore, EcstoreError, Endpoint, EndpointServerPools,
+        Endpoints, IlmAction, LcEvent, LcEventSrc, MockWarmBackend, PoolEndpoints, STORAGE_FORMAT_FILE, TransitionOptions,
+        assert_transition_meta_consistent, enqueue_transition_for_existing_objects, expire_transitioned_object,
+        free_version_count, get_bucket_metadata, get_global_tier_config_mgr, init_background_expiry, init_bucket_metadata_sys,
+        init_local_disks, is_err_object_not_found, is_err_version_not_found, new_disk, path2_bucket_object_with_base_path,
+        register_mock_tier_util, update_bucket_metadata, wait_for_free_version_absence,
     };
 }