Merge branch 'pratik/otel-phase10-workload-validation' into pratik/otel-sync-diagnostics

Brings in the phase-10 revert of the nodestore read-latency histogram plus the
nudb_bytes -> stored_object_bytes rename.

Conflicts in MetricsRegistry.{h,cpp} resolved keeping both intents:

- MetricsRegistry.cpp: dropped everything that existed only to serve the
  reverted nodestore_read_us histogram -- the addSubMillisecondHistogramView()
  helper, its call site, the kSubMillisecondBoundaries array and the
  NodeStoreMetricNames.h include. Kept every view this branch registers
  (consensus round duration, sweep_malloc_trim_us, dns_resolve_latency_ms,
  overlay_dial_latency_ms) and the shared addHistogramView() base helper.
  Took the rename at the storage_detail observe() call site.

- MetricsRegistry.h: took phase-10's move of the four nodestore_state observe
  helpers and their ObserveFn sink from private to public, while keeping this
  branch's enriched Doxygen on observeNodeStoreTotals().

Also corrected the registered-view count in the 09 reference doc: neither side's
arithmetic survives the merge, since this branch adds four views phase-10 never
saw and the revert removes one. Ten views are registered now, not six or seven.

docker/telemetry/workload/expected_metrics.json

@@ -125,7 +125,7 @@
   },
   "parity_storage": {
     "description": "External dashboard parity: storage detail metrics (MetricsRegistry).",
-    "metrics": ["storage_detail{metric=\"nudb_bytes\"}"]
+    "metrics": ["storage_detail{metric=\"stored_object_bytes\"}"]
   },
   "sync_diagnostics": {
     "description": "Fresh-node sync diagnostics (native metrics). Bootstrap (Domain 0) and acquire-pipeline signals rendered by the ledger-sync-health dashboard. Names are appended one per signal. Histograms are listed by their Prometheus _bucket series (the bare instrument name is not a series). The two observable gauges carry an inline metric= selector so the specific sub-series is asserted, matching the parity_* groups.",