Fix typo which trigger performance bug #35216 : Fixed failing integration test

Author: engcom-Echo

app/code/Magento/Catalog/Model/ResourceModel/Category/Collection.php

@@ -556,7 +556,8 @@ private function getProductsCountFromCategoryTable(Category $item, string $websi
      */
     private function getProductsCountQuery(array $categoryIds, $addVisibilityFilter = true): Select
     {
-        $categoryTable = $this->getTable('catalog_category_product_index');
+        $connections = $this->_resource->getConnection();
+        $categoryTable = $connections->getTableName('catalog_category_product_index');
         $select = $this->_conn->select()
             ->from(
                 ['cat_index' => $categoryTable],

dev/tests/integration/testsuite/Magento/Catalog/Block/Adminhtml/Category/Checkboxes/TreeTest.php

@@ -21,6 +21,7 @@
  *
  * @magentoAppArea adminhtml
  * @magentoDbIsolation enabled
+ * @magentoAppIsolation enabled
  */
 class TreeTest extends TestCase
 {