fix(supergroups): add backfill referrer to Referrer enum (#113092)

Add the referrer for the supergroups backfill job.

Co-authored-by: Claude <noreply@anthropic.com>

Author: cvxluo

src/sentry/snuba/referrer.py

@@ -786,6 +786,9 @@ class Referrer(StrEnum):
     SEER_EXPLORER_INDEX = "seer.explorer_index"
     SEER_EXPLORER_SERVICE_MAP = "seer.explorer_service_map"
     SEER_EXPLORER_TOOLS = "seer.explorer_tools"
+    SUPERGROUPS_BACKFILL_LIGHTWEIGHT_GET_LATEST_EVENTS = (
+        "supergroups_backfill_lightweight.get_latest_events"
+    )
     SERIALIZERS_GROUPSERIALIZERSNUBA__EXECUTE_ERROR_SEEN_STATS_QUERY = (
         "serializers.GroupSerializerSnuba._execute_error_seen_stats_query"
     )

src/sentry/tasks/seer/backfill_supergroups_lightweight.py

@@ -17,6 +17,7 @@
 )
 from sentry.services.eventstore.models import Event
 from sentry.snuba.dataset import Dataset
+from sentry.snuba.referrer import Referrer
 from sentry.tasks.base import instrumented_task
 from sentry.taskworker.namespaces import seer_tasks
 from sentry.types.group import UNRESOLVED_SUBSTATUS_CHOICES
@@ -280,7 +281,7 @@ def _batch_fetch_events(groups: Sequence[Group], organization_id: int) -> list[t
         )
 
     results = bulk_snuba_queries(
-        snuba_requests, referrer="supergroups_backfill_lightweight.get_latest_events"
+        snuba_requests, referrer=Referrer.SUPERGROUPS_BACKFILL_LIGHTWEIGHT_GET_LATEST_EVENTS.value
     )
 
     # Build unfetched Event objects from Snuba results, keeping groups aligned