fix(ui): Fix "Missing queryFn" error in useAggregatedQueryKeys

QueryObserver was created without a queryFn to listen for when
fetchQuery resolved. In TanStack Query v5 this throws "Missing queryFn"
whenever the observer evaluates stale data. Fires on every batch of IDs
buffered through useReplayCount so it spams on any issue list page.

Replace the observer with .finally() on the fetchQuery promise to clean
up inFlight markers — simpler and doesn't need the subscription ref
cleanup.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: scttcper

static/app/utils/api/useAggregatedQueryKeys.tsx

@@ -4,12 +4,10 @@ import type {ApiResult} from 'sentry/api';
 import {defined} from 'sentry/utils';
 import {uniq} from 'sentry/utils/array/uniq';
 import type {ApiQueryKey} from 'sentry/utils/queryClient';
-import {fetchDataQuery, QueryObserver, useQueryClient} from 'sentry/utils/queryClient';
+import {fetchDataQuery, useQueryClient} from 'sentry/utils/queryClient';
 
 const BUFFER_WAIT_MS = 20;
 
-type Subscription = () => void;
-
 interface Props<AggregatableQueryKey, Data> {
   /**
    * The queryKey reducer
@@ -90,14 +88,6 @@ export function useAggregatedQueryKeys<AggregatableQueryKey, Data>({
 
   const key = getQueryKey([]).at(0);
 
-  const subscriptions = useRef<Subscription[]>([]);
-  useEffect(() => {
-    const subs = subscriptions.current;
-    return () => {
-      subs.forEach(unsubscribe => unsubscribe());
-    };
-  }, []);
-
   // The query keys that this instance cares about
   const prevQueryKeys = useRef<AggregatableQueryKey[]>([]);
 
@@ -148,19 +138,17 @@ export function useAggregatedQueryKeys<AggregatableQueryKey, Data>({
       });
 
       const queryKey = getQueryKey(queuedAggregatableBatch);
-      queryClient.fetchQuery({
-        queryKey,
-        queryFn: fetchDataQuery,
-      });
-
-      const observer = new QueryObserver(queryClient, {queryKey});
-      const unsubscribe = observer.subscribe(_result => {
-        queryClient.removeQueries({
-          queryKey: ['aggregate', cacheKey, key, 'inFlight'],
-          predicate: isQueryKeyInBatch,
+      queryClient
+        .fetchQuery({
+          queryKey,
+          queryFn: fetchDataQuery,
+        })
+        .finally(() => {
+          queryClient.removeQueries({
+            queryKey: ['aggregate', cacheKey, key, 'inFlight'],
+            predicate: isQueryKeyInBatch,
+          });
         });
-      });
-      subscriptions.current.push(unsubscribe);
 
       if (allQueuedQueries.length > queuedQueriesBatch.length) {
         fetchData();