fix: address review feedback on batch-size default, requirements-local, docstring

- NOTIFICATION_QUEUE_BATCH_SIZE default reverted to 0 (unlimited) -- the
  existing behavior before this ticket, so deployments must opt in to the
  cap rather than having it silently applied at 5000
- requirements-local.txt: bump sientia_do pin to 1.12.3 to match requirements.txt
- Trim the load_latest_data docstring addition so it reads as documentation,
  not a changelog entry

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

orchestrator/activities/mongo_db.py

@@ -451,15 +451,9 @@ class MongoDB(SientiaMonitoring):
         filtering by timestamp to enable incremental data processing. It
         handles connection management and provides comprehensive error reporting.
 
-        SIENTIAPDE-2013: the query is capped at ``notification_queue_batch_size``
-        documents (hard cap per run, no drain loop) and sorted by ``timestamp``
-        ascending, so a capped run always returns the *oldest* pending documents
-        first. That matters because the caller advances its incremental cursor to
-        the max timestamp of whatever this returns -- without the ascending sort,
-        a capped batch could skip over older documents that never get picked up
-        on a later run. This backstops a cold start, backlog buildup, or
-        notification storm from fetching an unbounded (and potentially
-        multi-megabyte) payload in one query.
+        The query is capped at ``notification_queue_batch_size`` documents and sorted by
+        ``timestamp`` ascending, so a capped run returns the oldest pending documents first --
+        the caller advances its cursor only to what was actually returned, so nothing is skipped.
 
         Args:
             input_data (dict[str, Any]): Activity input parameters.

orchestrator/utils/connectors_config.py

@@ -33,7 +33,7 @@ def build_mongodb_config():
         'connection_string': connection_string,
         'database_name': getenv('MONGODB_DATABASE_NAME', 'sientia'),
         'ttl_index_seconds': int(getenv('MONGODB_TTL_INDEX_HOURS', '1')) * 3600,
-        'notification_queue_batch_size': int(getenv('NOTIFICATION_QUEUE_BATCH_SIZE', '5000')),
+        'notification_queue_batch_size': int(getenv('NOTIFICATION_QUEUE_BATCH_SIZE', '0')),
     }