MINOR: Reset list test helper capacity

Author: prashanthbdremio

vector/src/test/java/org/apache/arrow/vector/testing/ValueVectorDataPopulator.java

@@ -633,9 +633,10 @@ public static void setVector(LargeVarCharVector vector, String... values) {
 
   /** Populate values for {@link ListVector}. */
   public static void setVector(ListVector vector, List<Integer>... values) {
-    vector.allocateNewSafe();
     Types.MinorType type = Types.MinorType.INT;
     vector.addOrGetVector(FieldType.nullable(type.getType()));
+    vector.setInitialCapacity(values.length);
+    vector.allocateNewSafe();
 
     IntVector dataVector = (IntVector) vector.getDataVector();
     dataVector.allocateNew();
@@ -662,9 +663,10 @@ public static void setVector(ListVector vector, List<Integer>... values) {
 
   /** Populate values for {@link LargeListVector}. */
   public static void setVector(LargeListVector vector, List<Integer>... values) {
-    vector.allocateNewSafe();
     Types.MinorType type = Types.MinorType.INT;
     vector.addOrGetVector(FieldType.nullable(type.getType()));
+    vector.setInitialCapacity(values.length);
+    vector.allocateNewSafe();
 
     IntVector dataVector = (IntVector) vector.getDataVector();
     dataVector.allocateNew();