adapter: collect durable replica hydration history

Extend the hydration history sweep to record the latest completed replica episode after collecting per-object rows. Derive episode boundaries from connected object hydration intervals and wait for every configured process before snapshotting resource peaks.

Use the maximum cgroup memory peak and filesystem or swap peak across processes, retain rows with the existing 30-day policy, and cover incremental hydration, restart durability, deduplication, and retention.

Author: aljoscha

doc/user/data/metrics.yml

@@ -963,7 +963,7 @@ metrics:
   source: src/adapter/src/metrics.rs
   visibility: internal
 - name: mz_hydration_history_retention_batch_full_total
-  help: Total hydration-history sweeps whose retention batch was full. Repeated increments mean retention may not be keeping up with its schedule.
+  help: Total hydration-history retention batches that were full. Repeated increments mean retention may not be keeping up with its schedule.
   source: src/adapter/src/metrics.rs
   visibility: internal
 - name: mz_hydration_history_rows_affected_total

src/adapter-types/src/dyncfgs.rs

@@ -421,19 +421,19 @@ pub const ARRANGEMENT_SIZE_HISTORY_RETENTION_PERIOD: Config<Duration> = Config::
     ParameterScope::Environment,
 );
 
-/// How often to sweep replicas for completed object hydration episodes.
+/// How often to sweep replicas for completed object and replica hydration episodes.
 pub const HYDRATION_HISTORY_COLLECTION_INTERVAL: Config<Duration> = Config::new(
     "hydration_history_collection_interval",
     Duration::ZERO,
-    "How often to record completed object hydration episodes. A zero duration disables collection.",
+    "How often to record completed object and replica hydration episodes. A zero duration disables collection.",
     ParameterScope::Environment,
 );
 
-/// How long to retain completed object hydration episodes.
+/// How long to retain completed object and replica hydration episodes.
 pub const HYDRATION_HISTORY_RETENTION_PERIOD: Config<Duration> = Config::new(
     "hydration_history_retention_period",
     Duration::from_hours(30 * 24),
-    "How long to retain rows in mz_internal.mz_object_hydration_history.",
+    "How long to retain rows in mz_internal.mz_object_hydration_history and mz_internal.mz_replica_hydration_history.",
     ParameterScope::Environment,
 );