WebUI: simplify removing elements from an array

Now it remove elements starting from the end of an array which should have better performance
and succinct code.

Author: Chocobo1

src/webui/www/private/scripts/dynamicTable.js

@@ -872,11 +872,9 @@ window.qBittorrent.DynamicTable ??= (() => {
         updateTable(fullUpdate = false) {
             const rows = this.getFilteredAndSortedRows();
 
-            for (let i = 0; i < this.selectedRows.length; ++i) {
-                if (!(this.selectedRows[i] in rows)) {
+            for (let i = this.selectedRows.length - 1; i >= 0; --i) {
+                if (!(this.selectedRows[i] in rows))
                     this.selectedRows.splice(i, 1);
-                    --i;
-                }
             }
 
             if (this.useVirtualList) {