feat(starfish): reduce span summary pagesize (#53194)

- Reduce the pagesize on the span summary page from 50 to 25 now that
page size can have an impact on performance.

static/app/views/starfish/queries/useSpanTransactionMetrics.tsx

@@ -40,6 +40,7 @@ export const useSpanTransactionMetrics = (
     eventView,
     initialData: [],
     enabled: Boolean(span),
+    limit: 25,
     referrer: _referrer,
   });
 };