* perf(ecstore): memoize bucket-incarnation fence validation under lifecycle read-lock coverage
The PUT commit fence from #5648 validated the bucket incarnation with an uncached read (a distributed metadata-transaction read lock plus an EC quorum read of bucket metadata) on every PUT commit. Under 64-concurrency 4KiB PUT load this adds two quorum round-trips per PUT and the resulting lock-manager pressure produced ~1,000 client-visible 'Lock acquisition timeout' failures per 5-minute window (see rustfs/backlog#1776).
Memoize the validation per node while lifecycle read-lock coverage is continuous: bucket deletion/recreation requires the lifecycle WRITE lock, so while at least one read guard on this node has been held continuously the incarnation cannot have changed. The first fenced PUT in a coverage window performs the exact authoritative disk validation as before; overlapping PUTs reuse its result. The memo clears when the node's last guard drops or any guard observes a lost lock, so the next PUT revalidates from disk. Fence semantics are unchanged; only the redundant re-validations under continuous coverage are elided.
Also right-size the s3s footprint ratchet baselines: -1 s3_error! line from this change's error-path consolidation, and +1 s3s-importing file inherited from #5763 (crates/obs/src/telemetry/filter.rs) which landed on main without the baseline bump.
* fix(ecstore): carry the bucket fence registry through the rebalance test store
The rebalance entry test constructor landed on main after this branch was cut and needs the new field.
cxymds