Fix over-counted site availability: exclude future advance reservations

occupied_node_capacity() now defaults to start=now, end=now when no time
range is specified. Previously, all Ticketed reservations (including future
advance reservations) were counted as currently occupied, causing
cores_allocated to exceed cores_capacity at sites like UCSD (657 > 640).
Calendar/scheduling callers that pass explicit start/end are unaffected.

Author: kthare10

fabric_cf/actor/fim/plugins/broker/aggregate_bqm_plugin.py

@@ -26,7 +26,7 @@
 from __future__ import annotations
 
 import json
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Tuple, Dict, TYPE_CHECKING, List, Optional
 from collections import defaultdict
 
@@ -167,6 +167,15 @@ def occupied_node_capacity(*, db: ABCDatabase, node_id: str, start: Optional[dat
                   ReservationStates.Ticketed.value,
                   ReservationStates.Nascent.value]
 
+        # When no time range is specified, default to "now" so that future
+        # advance reservations (Ticketed state) are not counted as currently
+        # occupied.  Callers that need future availability (e.g. the calendar
+        # endpoint) pass explicit start/end and are unaffected.
+        if start is None and end is None:
+            now = datetime.now(timezone.utc)
+            start = now
+            end = now
+
         # get existing reservations for this node
         existing_reservations = db.get_reservations(graph_node_id=node_id, states=states, start=start, end=end)
         # node capacities