fix(typing): Use subscript access for required event_id in delayed_processing

`event_id` is a required key in `EventData` TypedDict, so use
`instance_data["event_id"]` instead of `.get()`. Remove the dead
None-check branch since it can never be reached.

Ref: #107727

Author: JoshFerge

src/sentry/rules/processing/delayed_processing.py

@@ -296,17 +296,10 @@ def build_group_to_groupevent(
     group_to_groupevent: dict[Group, tuple[GroupEvent, datetime | None]] = {}
 
     for rule_group, instance_data in parsed_rulegroup_to_event_data.items():
-        event_id = instance_data.get("event_id")
+        event_id = instance_data["event_id"]
         occurrence_id = instance_data.get("occurrence_id")
         start_timestamp = instance_data.get("start_timestamp")
 
-        if event_id is None:
-            logger.info(
-                "delayed_processing.missing_event_id",
-                extra={"rule": rule_group[0], "project_id": project_id},
-            )
-            continue
-
         event = bulk_event_id_to_events.get(event_id)
         group = group_id_to_group.get(int(rule_group[1]))