fix: adding dataset hierarchical item shouldn't cause scroll flickeri…

…ng (#1076)

- calling `datasetHierarchical` setter shouldn't cause scroll flickering, this was caused a call to the DataView `setItems` with an empty array that was meant to clear the dataset before recreating it, however this is certainly not needed since calling the `datasetHierarchical` setter will then trigger a new sort which will indirectly call DataView setItems anyway

packages/vanilla-bundle/src/components/slick-vanilla-grid-bundle.ts

@@ -193,7 +193,6 @@ export class SlickVanillaGridBundle {
 
     // when a hierarchical dataset is set afterward, we can reset the flat dataset and call a tree data sort that will overwrite the flat dataset
     if (this.dataView && newHierarchicalDataset && this.slickGrid && this.sortService?.processTreeDataInitialSort) {
-      this.dataView.setItems([], this._gridOptions?.datasetIdPropertyName ?? 'id');
       this.sortService.processTreeDataInitialSort();
 
       // we also need to reset/refresh the Tree Data filters because if we inserted new item(s) then it might not show up without doing this refresh