Data: use pre-defined output array length in vectorToArray() (#29516)

packages/grafana-data/src/vector/vectorToArray.ts

@@ -1,7 +1,7 @@
 import { Vector } from '../types/vector';
 
 export function vectorToArray<T>(v: Vector<T>): T[] {
-  const arr: T[] = [];
+  const arr: T[] = Array(v.length);
   for (let i = 0; i < v.length; i++) {
     arr[i] = v.get(i);
   }