fix(storage): sync transition tier config across peers

[cxymds]

Related Issues

Fixes #2153

Summary of Changes

• Reload transition tier configuration from shared storage before add, edit, and remove admin mutations.
• Propagate successful transition tier configuration saves to peer nodes through load_transition_tier_config.
• Implement the peer RPC handler for loading transition tier configuration locally.
• Add focused regression coverage for the tier config reload RPC and unreachable peer reporting.

Verification

• cargo fmt --all --check
• cargo test test_unimplemented_rpcs --package rustfs --lib -- --nocapture
• cargo test test_load_transition_tier_config_no_object_layer --package rustfs --lib --ignored --nocapture
• cargo test load_transition_tier_config_reports_unreachable_peers -p rustfs-ecstore --lib -- --nocapture
• cargo test load_bucket_metadata_reports_unreachable_peers -p rustfs-ecstore --lib -- --nocapture
• NUM_CORES=1 CARGO_BUILD_JOBS=1 TEST_THREADS=1 CARGO_INCREMENTAL=0 CARGO_PROFILE_DEV_DEBUG=0 CARGO_PROFILE_TEST_DEBUG=0 make -f <(printf '.NOTPARALLEL:\ninclude Makefile\n') pre-commit

Impact

Transition tier configuration changes are now reloaded from shared storage before mutation and propagated to peer nodes after a successful local save. Peer propagation failures are logged and do not roll back the already-saved local admin operation.

Additional Notes

cargo-nextest was not installed locally, so make pre-commit used the repository fallback to cargo test.

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[Copilot]

Pull request overview

This PR ensures transition tier configuration changes are consistently applied across a RustFS cluster by reloading the latest config before local mutations and triggering peer nodes to reload after a successful save via the internode notification/RPC path.

Changes:

• Implement load_transition_tier_config RPC on NodeService to reload GLOBAL_TierConfigMgr from the object store.
• Reload tier config from the object store before Add/Edit/Remove tier admin operations, and propagate the update to peers after local save.
• Add a regression test ensuring peer propagation reports unreachable peers for transition-tier reload notifications.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
rustfs/src/storage/rpc/node_service.rs	Implements the peer RPC handler that reloads transition tier config from the object store and updates tests accordingly.
rustfs/src/admin/handlers/tier.rs	Reloads tier config before mutations and triggers best-effort peer reload notifications after local save for add/edit/remove.
crates/ecstore/src/notification_sys.rs	Adds a focused test covering unreachable peer reporting for transition-tier config reload propagation.